16 kbit/s TRAU frame format for the AMR speech · PDF file16 kbit/s TRAU frame format for the AMR speech service ... 4.7.1.5 Procedures for 16 kbit/s intermediate rate adaption rate

1/1

ETSI TC SMG TD SMG P-99-218Meeting #28 Agenda item: 6.2Milano, Italy8th - 12th February, 1999

ETSI/TC/SMG/SMG2 Tdoc SMG2 167R/99

Liaison statement from SMG2 to TC/SMGCopy to SMG11

16 kbit/s TRAU frame format for the AMR speech service

Two proposals were made to SMG2 regarding the TRAU frame format at 16 kbit/s for the AMR speechservice. A drafting group met in order to converge toward a single proposal.

No final agreement was reached. It was however felt premature to approve a CR on the TS GSM 08.60since some details of the AMR TFO were not known and it was recognized that they could impact theTRAU frame and their related procedures. Most likely both solutions are viable for AMR.

Two CRs were produced “for information” to SMG #28 and are attached to this Liaison Statement.

The proposal A (SMG2 Tdoc 168/99) partly reuses the existing format specified for GSM FR and EFRin the TS GSM 08.60. The existing synchronization mechanisms are conserved but no room is left forfuture evolutions beyond AMR.

The proposal B (SMG2 Tdoc 169/99) enables higher net bit rates using mechanisms developed for the14,4 kbit/s data service. This could likely be required for the 8 kbit/s AMR TRAU frame format. It isfelt that this format could be re-used for future evolutions beyond AMR. It is nevertheless recognizedthat it is slightly more complex than the proposal A.

SMG2 feel confident that a single solution including the necessary means for Tandem Free Operationwill be presented “for approval” to SMG #29. This will be presented together with the CRs related tothe AMR introduction on the TS GSM 08.61 (TRAU frames for TCH/H) and on the future TS GSM08.62 (In Band TFO).

ETSI SMG2 Tdoc SMG2 168 / 99Sophia-Antipolis, FranceJanuary 25-29, 1999

CHANGE REQUEST No : A008_rev2A

Please see embedded help file at the bottom of thispage for instructions on how to fill in this form correctly.

Technical Specification GSM / UMTS: 08.60 Version: 5.1.1

Submitted to SMG #28 for approval without presentation ("non-strategic") Xlist SMG plenary meeting no. here ↑ for information X with presentation ("strategic")

PT SMG CR cover form. Filename: crf26_3.doc

Proposed change affects: SIM ME Network X(at least one should be marked with an X)

Work item: AMR (Adaptive Multi-Rate Speech Codec)

Source: SMG2 drafting group Date: Jan 27, 1999

Subject: Introduction of AMR in 08.60

Category: F Correction Release: Phase 2A Corresponds to a correction in an earlier release Release 96

(one category B Addition of feature X Release 97and one release C Functional modification of feature Release 98 Xonly shall be D Editorial modification Release 99marked with an X) UMTS

Reason forchange:

Introduction of AMR

Clauses affected:

Other specs Other releases of same spec → List of CRs:affected: Other core specifications → List of CRs:

MS test specifications / TBRs → List of CRs:BSS test specifications → List of CRs:O&M specifications → List of CRs:

Othercomments:

This is Proposal A (Ericsson, Nokia, Siemens).For Proposal B (Alcatel, Nortel), see CR A008_rev2B, SMG2 TD 169/99.

help.doc

<--------- double-click here for help and instructions on how to create a CR.

EUROPEAN ETS 300 737_AMR

TELECOMMUNICATION Febuary 19998

STANDARD Second Edition

Source: SMG Reference: RE/SMG-020860QR1

ICS: 33.020

Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)

GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS

R

Digital cellular telecommunications system (Phase 2+);Inband control of remote transcoders and rate adaptors for

Enhanced Full Rate (EFR) and fFull r Rate (FR) traffic channels(GSM 08.60 version 5.1.1_AMR)

ETSI

European Telecommunications Standards Institute

ETSI Secretariat

Postal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [email protected]

Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16

Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoingrestriction extend to reproduction in all media.

© European Telecommunications Standards Institute 1998. All rights reserved.

Page 2ETS 300 737 (GSM 08.60 version 5.1.1_AMR): FebrJanuary 19998

Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to "ETSI Editingand Committee Support Dept." at the address shown on the title page.


Contents

Foreword .......................................................................................................................................................................5

1 Scope ..........................................................................................................................................................................71.1 Normative references ...................................................................................................................................71.2 Abbreviations ...............................................................................................................................................8

2 General Approach.......................................................................................................................................................8

3 Frame Structure ........................................................................................................................................................113.1 Speech Frames for FR, EFR and AMR ......................................................................................................113.2 O&M Frames..............................................................................................................................................133.3 Data Frames ...............................................................................................................................................14

3.3.1 Data Frame (for Synchronisation) ..........................................................................................143.3.2 Extended data frame (E-TRAU : data transport) ....................................................................15

3.4 Idle Speech Frames ....................................................................................................................................163.5 Coding........................................................................................................................................................16

3.5.1.1 Coding of Speech Frames for FR and EFR .........................................................................173.5.1.2 Coding of Speech Frames for AMR ....................................................................................193.5.2 Coding of O&M Frames.........................................................................................................233.5.3 Coding of Data Frames...........................................................................................................233.5.4 Coding of Extended Data Frames...........................................................................................233.5.5 Coding of Idle Speech Frames................................................................................................23

3.6. Order of Bit Transmission.........................................................................................................................24

4 Procedures ................................................................................................................................................................244.1 Remote Control of Transcoders and Rate Adaptors ...................................................................................244.2 Resource Allocation ...................................................................................................................................244.3 Resource Release........................................................................................................................................254.4 In Call Modification...................................................................................................................................254.5 Transfer of Idle Frames ..............................................................................................................................25

4.5.1 In Full rate data case:..............................................................................................................254.5.2 In Full rate speech case: .........................................................................................................264.5.3 In Enhanced Full rate speech case:.........................................................................................264.5.4 In Adaptive Multi-Rate speech case:......................................................................................26

4.6 Procedures for Speech Frames ...................................................................................................................264.6.1 Time Alignment of Speech Frames ........................................................................................26

4.6.1.1 Initial Time Alignment State.........................................................................264.6.1.2 The Static Time Alignment State ..................................................................274.6.1.2.1 Time Alignment of Codec_Mode_Indication for AMR.............................274.6.1.3 Initiation at Resource Allocation ..................................................................294.6.1.4 Time Alignment During Handover ...............................................................29

4.6.1.4.1 BSS External Handover .................................................294.6.1.4.2 BSS Internal Handover ..................................................29

4.6.2 Procedures for Discontinuous Transmission (DTX) ..............................................................294.6.2.1 DTX procedures in the uplink direction........................................................294.6.2.2 DTX procedures in the downlink direction...................................................29

4.7 Procedures for Data Frames .......................................................................................................................304.7.1 9.6 and 4.8 kbit/s channel coding ............................................................................................................30

4.7.1.1 The RAA Function ..............................................................................................................304.7.1.2 The RA1/RA1' Function......................................................................................................314.7.1.3 The RA2 Function...............................................................................................................314.7.1.4 Procedures for 8 kbit/s intermediate rate adaption rate .......................................................314.7.1.5 Procedures for 16 kbit/s intermediate rate adaption rate .....................................................314.7.1.6 Support of Non-Transparent Bearer Applications...............................................................31

4.7.2 14.5 kbit/s channel coding.......................................................................................................................32


4.7.2.1 The RAA’ Function.............................................................................................................324.7.2.2 The RA1’/RAA' Function....................................................................................................324.7.2.3 The RA2 Function...............................................................................................................32

4.8 Frame Synchronization...............................................................................................................................324.8.1 Search for Frame Synchronization .........................................................................................324.8.2 Frame Synchronization After Performing Downlink Timing Adjustments ............................324.8.3 Frame Synchronization Monitoring and Recovery.................................................................33

4.9 Correction/detection of bit errors on the terrestrial circuits........................................................................344.9.1 Error Detection on the Control Bits........................................................................................34

4.9.1.1 General Procedure ........................................................................................344.9.1.2 Speech Frames ..............................................................................................34

4.9.2 Handling of frames received with errors ................................................................................344.9.2.1 In case of Full Rate: ......................................................................................344.9.2.2 In case of Enhanced Full rate and Adaptive Multi-Rate: ..............................34

4.10 Procedures for Operation & Maintenance................................................................................................354.10.1 Transfer of O&M Information Between the TRAU and the BSC ........................................354.10.2 Procedures in the TRAU ......................................................................................................354.10.3 Procedures in the BSC..........................................................................................................35

4.10.3.1 Use of O&M Frames...................................................................................354.10.4 Procedures in the BTS..........................................................................................................35

History.........................................................................................................................................................................37


ForewordThis European Telecommunication Standard (ETS) has been produced by the Special Mobile Group(SMG) of the European Telecommunications Standards Institute (ETSI).

This ETS specifies the inband control of remote transcoders and rate adaptors for full rate speech,Enhanced Full rate speech and full rate data within the Digital cellular telecommunications system(Phase 2+).

The specification from which this ETS has been derived was originally based on CEPT documentation,hence the presentation of this ETS may not be entirely in accordance with the ETSI/PNE Rules.

Transposition dates

Date of adoption of this ETS: 23 January 1998

Date of latest announcement of this ETS (doa): 31 May 1998

Date of latest publication of new National Standardor endorsement of this ETS (dop/e): 30 November 1998

Date of withdrawal of any conflicting National Standard (dow): 30 November 1998


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1 ScopeWhen 64 kbit/s traffic channels are used on the Abis interface, the speech shall be coded according toCCITT Recommendation G.711 and the data rate adaptation shall be as specified in GSM 04.21 andGSM 08.20.

In the case where 16 kbit/s traffic channels are used for full rate speech or enhanced full rate speech oradaptive multi-rate speech or full rate data service, then this specification shall apply for frame structureand for control of remote transcoders and additional rate adaptors.

The use and general aspects of the Abis interface are given in GSM 08.51.

NOTE: This specification should be considered together with the GSM 06 series of specifications,GSM 04.21 (Rate Adaptation on the MS-BSS Interface) and GSM 08.20 (Rate Adaptation onthe BS/MSC Interface).

1.1 Normative referencesThis ETS incorporates by dated and undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listedhereafter. For dated references, subsequent amendments to or revisions of any of these publicationsapply to this ETS only when incorporated in it by amendment or revision. For undated references, thelatest edition of the publication referred to applies.

[1] GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+);Abbreviations and acronyms".

[2] GSM 04.06 (ETS 300 938): "Digital cellular telecommunications system; MobileStation - Base Station System (MS - BSS) interface; Data Link (DL) layerspecification".

[3] GSM 04.21 (ETS 300 945): "Digital cellular telecommunications system; Rate adaptionon the Mobile Station - Base Station System (MS - BSS) interface".

[4] GSM 06.01 (ETS 300 960): "Digital cellular telecommunications system; Full ratespeech; Processing functions".

[5] GSM 06.10 (ETS 300 961): "Digital cellular telecommunications system; Full ratespeech; Transcoding".

[6] GSM 06.11 (ETS 300 962): "Digital cellular telecommunications system; Full ratespeech; Substitution and muting of lost frames for full rate speech channels".

[7] GSM 06.12 (ETS 300 963): "Digital cellular telecommunications system; Full ratespeech; Comfort noise aspect for full rate speech traffic channels".

[8] GSM 06.31 (ETS 300 964): "Digital cellular telecommunications system; Full ratespeech; Discontinuous Transmission (DTX) for full rate speech traffic channels".

[9] GSM 06.32 (ETS 300 965): "Digital cellular telecommunications system; VoiceActivity Detector (VAD)".

[10] GSM 08.20: "Digital cellular telecommunications system; Rate adaption on the BaseStation System - Mobile-services Switching Centre (BSS - MSC) interface".

[11] GSM 08.51: "Digital cellular telecommunications system; Base Station Controller -Base Transceiver Station (BSC - BTS) interface; General aspects".

[12] GSM 08.54: "Digital cellular telecommunications system (Phase 2+); Base StationController - Base Transceiver Station (BSC - BTS) interface; Layer 1 structure ofphysical circuits".

[13] GSM 08.58: "Digital cellular telecommunications system (Phase 2+); Base StationController - Base Transceiver Station (BSC - BTS) interface; Layer 3 specification".

[14] GSM 12.21 (ETS 300 623): "Digital cellular telecommunications system (Phase 2);Network Management (NM) procedures and message on the A-bis interface".

[15] CCITT Recommendation G.711: "Pulse code modulation (PCM) of voice frequencies".[16] CCITT Recommendation I.460: "Multiplexing, rate adaption and support of existing

interfaces".[17] CCITT Recommendation V.110: "Support of data terminal equipments (DTEs) with V-

Series interfaces by an integrated services digital network".[18] GSM 06.51 (ETS 300 723): "Digital cellular telecommunications system; Enhanced Full

rate speech processing functions".[19] GSM 06.60 (ETS 300 726): "Digital cellular telecommunications system; Enhanced Full

rate speech transcoding".[20] GSM 06.61 (ETS 300 727): "Digital cellular telecommunications system; Substitution

and muting of lost frames for Enhanced Full rate speech channels".


[21] GSM 06.62 (ETS 300 728): "Digital cellular telecommunications system; Comfort noiseaspect for Enhanced Full rate speech traffic channels".

[22] GSM 06.81 (ETS 300 729): "Digital cellular telecommunications system; DiscontinuousTransmission (DTX) for Enhanced Full rate speech traffic channel".

[23] GSM 06.82 (ETS 300 730): "Digital cellular telecommunications system; VoiceActivity Detection (VAD)".

[24] GSM 06.71: "Digital cellular telecommunications system; Adaptive Multi-Rate speechprocessing functions, General Description."

[25] GSM 06.90: "Digital cellular telecommunications system; Adaptive Multi-Rate speechtranscoding".

[26] GSM 06.91: "Digital cellular telecommunications system; Substitution and muting oflost frames for Adaptive Multi-Rate speech traffic channels".

[27] GSM 06.92: "Digital cellular telecommunications system; Comfort noise aspect forAdaptive Multi-Rate speech traffic channels".

[28] GSM 06.93: "Digital cellular telecommunications system; Discontinuous Transmission(DTX) for Adaptive Multi-Rate speech traffic channels".

[29] GSM 06.94: "Digital cellular telecommunications system; Voice Activity Detection(VAD) for Adaptive Multi-Rate speech traffic channels ".

[30] GSM 05.09: "Digital cellular telecommunications system; Link Adaptation"[31] GSM 08.61: " Digital cellular telecommunications system; In-band control of remote

transcoders and rate adaptors for half rate traffic channels".

1.2 AbbreviationsAbbreviations used in this specification are listed in GSM 01.04. Additionally:AMR: Adaptive Multi-Rate.

2 General ApproachWhen the transcoders/rate adaptors are positioned remote to the BTS, the information between theChannel Codec Unit (CCU) and the remote Transcoder/Rate Adaptor Unit (TRAU) is transferred in frameswith a fixed length of 320 bits (20 msmS). In this specification, these frames are denoted "TRAU frames".Within these frames, both the speech/data and the TRAU associated control signals are transferred.

The Abis interface should be the same if the transcoder is positioned 1) at the MSC site of the BSS or if itis positioned 2) at the BSC site of the BSS. In case 1), the BSC should be considered as transparent for16 kbit/s channels.

In case of 4,8 and 9,6 kbit/s channel coding when data is adapted to the 320 bit frames, a conversionfunction is required in addition to the conversion/rate adaption specified in GSM 08.20. This functionconstitutes the RAA. In case of 14,5 kbit/s channel coding, no RAA rate adaption is required becauseV.110 framing is not used.

The TRAU is considered a part of the BSC, and the signalling between the BSC and the TRAU (e.g.detection of call release, handover and transfer of O&M information) may be performed by using BSCinternal signals. The signalling between the CCU and the TRAU, using TRAU frames as specified in thisspecification, is mandatory when the Abis interface is applied.

NOTE: If standard 64 kbit/s switching is used in the BSC, multiplexing according to CCITTRecommendation I.460 should apply at both sides of the switch.

In figure 2.1, a possible configuration of the TRAU and the CCU is shown.

The functions inside the TRAU are:

- "Remote Transcoder and Rate Adaptor Control Function" (RTRACF);- "Remote Speech Handler Function" (RSHF);- The RAA function in case of 4.8 and 9.6 kbit/s channel coding;- The RAA’ function in case of 14,514.5 kbit/s channel coding;- The RA2 function;- The transcoder function.

The functions inside the CCU are:

- "Transcoder and Rate Adaptor Control Function" (TRACF);


- "Speech Handler Function" (SHF);- The RAA function in case of 4.8 and 9.6 kbit/s channel coding;- The RA1/RA1' function in case of 4.8 and 9.6 kbit/s channel coding;- The RA1’/RAA’ function in case of 14,514.5 kbit/s channel coding;- The channel codec function.

This specification will not describe the procedures inside the TRAU and the CCU. The layout in figure 2.1is only intended as a reference model.


Figure 2.1: Functional entities for handling of remote control of remote transcoders and rate adaptorsNOTE: This figure applies only for 4,8 and 9,6 kbit/s channel coding


3 Frame Structure3.1 Speech Frames3.1.1 Speech Frames for Full Rate and Enhanced Full Rate

Bit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 D1 D2 D3 D4 D5 D6 D75 D8 D9 D10 D11 D12 D13 D14 D156 1 D16 D17 D18 D19 D20 D21 D227 D23 D24 D25 D26 D27 D28 D29 D308 1 D31 D32 D33 D34 D35 D36 D379 D38 D39 D40 D41 D42 D43 D44 D4510 1 D46 D47 D48 D49 D50 D51 D5211 D53 D54 D55 D56 D57 D58 D59 D6012 1 D61 D62 D63 D64 D65 D66 D6713 D68 D69 D70 D71 D72 D73 D74 D7514 1 D76 D77 D78 D79 D80 D81 D8215 D83 D84 D85 D86 D87 D88 D89 D9016 1 D91 D92 D93 D94 D95 D96 D9717 D98 D99 D100 D101 D102 D103 D104 D10518 1 D106 D107 D108 D109 D110 D111 D11219 D113 D114 D115 D116 D117 D118 D119 D12020 1 D121 D122 D123 D124 D125 D126 D12721 D128 D129 D130 D131 D132 D133 D134 D13522 1 D136 D137 D138 D139 D140 D141 D14223 D143 D144 D145 D146 D147 D148 D149 D15024 1 D151 D152 D153 D154 D155 D156 D15725 D158 D159 D160 D161 D162 D163 D164 D16526 1 D166 D167 D168 D169 D170 D171 D17227 D173 D174 D175 D176 D177 D178 D179 D18028 1 D181 D182 D183 D184 D185 D186 D18729 D188 D189 D190 D191 D192 D193 D194 D19530 1 D196 D197 D198 D199 D200 D201 D20231 D203 D204 D205 D206 D207 D208 D209 D21032 1 D211 D212 D213 D214 D215 D216 D21733 D218 D219 D220 D221 D222 D223 D224 D22534 1 D226 D227 D228 D229 D230 D231 D23235 D233 D234 D235 D236 D237 D238 D239 D24036 1 D241 D242 D243 D244 D245 D246 D24737 D248 D249 D250 D251 D252 D253 D254 D25538 1 D256 D257 D258 D259 D260 C16 C1739 C18 C19 C20 C21 T1 T2 T3 T4


3.1.2 Speech Frames for Adaptive Multi- Rate

Bit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 C16 C17 C18 C19 C20 C21 D15 D2 D3 D4 D5 D6 D7 D8 D96 1 D10 D11 D12 D13 D14 D15 D167 D17 D18 D19 D20 D21 D22 D23 D248 1 D25 D26 D27 D28 D29 D30 D319 D32 D33 D34 D35 D36 D37 D38 D3910 1 D40 D41 D42 D43 D44 D45 D4611 D47 D48 D49 D50 D51 D52 D53 D5412 1 D55 D56 D57 D58 D59 D60 D6113 D62 D63 D64 D65 D66 D67 D68 D6914 1 D70 D71 D72 D73 D74 D75 D7615 D77 D78 D79 D80 D81 D82 D83 D8416 1 D85 D86 D87 D88 D89 D90 D9117 D92 D93 D94 D95 D96 D97 D98 D9918 1 D100 D101 D102 D103 D104 D105 D10619 D107 D108 D109 D110 D111 D112 D113 D11420 1 D115 D116 D117 D118 D119 D120 D12121 D122 D123 D124 D125 D126 D127 D128 D12922 1 D130 D131 D132 D133 D134 D135 D13623 D137 D138 D139 D140 D141 D142 D143 D14424 1 D145 D146 D147 D148 D149 D150 D15125 D152 D153 D154 D155 D156 D157 D158 D15926 1 D160 D161 D162 D163 D164 D165 D16627 D167 D168 D169 D170 D171 D172 D173 D17428 1 D175 D176 D177 D178 D179 D180 D18129 D182 D183 D184 D185 D186 D187 D188 D18930 1 D190 D191 D192 D193 D194 D195 D19631 D197 D198 D199 D200 D201 D202 D203 D20432 1 D205 D206 D207 D208 D209 D210 D21133 D212 D213 D214 D215 D216 D217 D218 D21934 1 D220 D221 D222 D223 D224 D225 D22635 D227 D228 D229 D230 D231 D232 D233 D23436 1 D235 D236 D237 D238 D239 D240 D24137 D242 D243 D244 D245 D246 D247 D248 D24938 1 D250 D251 D252 D253 D254 D255 D25639 C22 C23 C24 C25 T1 T2 T3 T4


3.2 O&M FramesBit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 D1 D2 D3 D4 D5 D6 D75 D8 D9 D10 D11 D12 D13 D14 D156 1 D16 D17 D18 D19 D20 D21 D227 D23 D24 D25 D26 D27 D28 D29 D308 1 D31 D32 D33 D34 D35 D36 D379 D38 D39 D40 D41 D42 D43 D44 D4510 1 D46 D47 D48 D49 D50 D51 D5211 D53 D54 D55 D56 D57 D58 D59 D6012 1 D61 D62 D63 D64 D65 D66 D6713 D68 D69 D70 D71 D72 D73 D74 D7514 1 D76 D77 D78 D79 D80 D81 D8215 D83 D84 D85 D86 D87 D88 D89 D9016 1 D91 D92 D93 D94 D95 D96 D9717 D98 D99 D100 D101 D102 D103 D104 D10518 1 D106 D107 D108 D109 D110 D111 D11219 D113 D114 D115 D116 D117 D118 D119 D12020 1 D121 D122 D123 D124 D125 D126 D12721 D128 D129 D130 D131 D132 D133 D134 D13522 1 D136 D137 D138 D139 D140 D141 D14223 D143 D144 D145 D146 D147 D148 D149 D15024 1 D151 D152 D153 D154 D155 D156 D15725 D158 D159 D160 D161 D162 D163 D164 D16526 1 D166 D167 D168 D169 D170 D171 D17227 D173 D174 D175 D176 D177 D178 D179 D18028 1 D181 D182 D183 D184 D185 D186 D18729 D188 D189 D190 D191 D192 D193 D194 D19530 1 D196 D197 D198 D199 D200 D201 D20231 D203 D204 D205 D206 D207 D208 D209 D21032 1 D211 D212 D213 D214 D215 D216 D21733 D218 D219 D220 D221 D222 D223 D224 D22534 1 D226 D227 D228 D229 D230 D231 D23235 D233 D234 D235 D236 D237 D238 D239 D24036 1 D241 D242 D243 D244 D245 D246 D24737 D248 D249 D250 D251 D252 D253 D254 D25538 1 D256 D257 D258 D259 D260 D261 D26239 D263 D264 S1 S2 S3 S4 S5 S6


3.3 Data Frames3.3.1 Data Frame (for Synchronisation)

Bit number

Octet no. 1 2 3 4 5 6 7 8

0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0

2 1 C1 C2 C3 C4 C5 C6 C7

3 C8 C9 C10 C11 C12 C13 C14 C15

4 1 .

5 1 .

6 1 .

7 1 Data frame position 1

8 1 63 bits.

9 1 (72 bits including bit position 1)

10 1

11 1

12 1

13 1

14 1

15 1


17 1

18 1

19 1

20 1

21 1

22 1

23 1

24 1


26 1

27 1

28 1

29 1

30 1

31 1

32 1


34 1

35 1

36 1

37 1

38 1

39 1


3.3.2 Extended data frame (E-TRAU : data transport)Bit number

Octet no. 1 2 3 4 5 6 7 8

0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0

2 1 C1 C2 C3 C4 C5 C6 C7

3 C8 C9 C10 C11 C12 C13 M1 M2

4 D1 D2 ...

5

6

7 Data block of 288 data bits and M1, M2.

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39 ... D287 D288


3.4 Idle Speech FramesBit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 1 1 1 1 1 1 15 1 1 1 1 1 1 1 16 1 1 1 1 1 1 1 17 1 1 1 1 1 1 1 18 1 1 1 1 1 1 1 19 1 1 1 1 1 1 1 110 1 1 1 1 1 1 1 111 1 1 1 1 1 1 1 112 1 1 1 1 1 1 1 113 1 1 1 1 1 1 1 114 1 1 1 1 1 1 1 115 1 1 1 1 1 1 1 116 1 1 1 1 1 1 1 117 1 1 1 1 1 1 1 118 1 1 1 1 1 1 1 119 1 1 1 1 1 1 1 120 1 1 1 1 1 1 1 121 1 1 1 1 1 1 1 122 1 1 1 1 1 1 1 123 1 1 1 1 1 1 1 124 1 1 1 1 1 1 1 125 1 1 1 1 1 1 1 126 1 1 1 1 1 1 1 127 1 1 1 1 1 1 1 128 1 1 1 1 1 1 1 129 1 1 1 1 1 1 1 130 1 1 1 1 1 1 1 131 1 1 1 1 1 1 1 132 1 1 1 1 1 1 1 133 1 1 1 1 1 1 1 134 1 1 1 1 1 1 1 135 1 1 1 1 1 1 1 136 1 1 1 1 1 1 1 137 1 1 1 1 1 1 1 138 1 1 1 1 1 1 C16 C1739 C18 C19 C20 C21 T1 T2 T3 T4

3.5 CodingIn the following sections, the coding of the frames is described. Any spare or not used control bits shouldbe coded binary "1".

For all frame types the octet 0, 1 and the first bit of octets 2, 4, 6, 8, ... 38 are used as frame sync.


3.5.1 Coding of Speech Frames3.5.1.1 Coding of Speech Frames for Full Rate and Enhanced Full Rate

Control bits (C-bits):

Description Uplink Downlink

C1C2C3C4 C5 C1C2C3C4 C5Frame type FR Speech: 0 0 0 1 0. Speech: 1 1 1 0 0(Bits C1 - C5). EFR Speech: 1 1 0 1 0 Speech: 1 1 0 1 0

Time Binary number indicating the Binary number indicatingAlignment required timing adjustment to the timing adjustment made.(Bits C6 - C11) be made in steps of 250/500 µs.

The following values apply for the codingC6C7 . . . C11 0 0 0 0 0 0 No change in frame timing 0 0 0 0 0 1 Delay frame 1 x 500 µs 0 0 0 0 1 0 Delay frame 2 x 500 µs . . . .... . . . .... 1 0 0 1 1 1 Delay frame 39 x 500 µs 1 0 1 0 0 0 Not used . . . .... 1 1 1 1 0 1 Not used 1 1 1 1 1 0 Delay frame 1 x 250 µs 1 1 1 1 1 1 Advance frame 250 µs

Frame indicators. The definition C12: BFI C12 - C15: Spareand coding of these indicators 0 : BFI = 0are given in GSM 06.31. 1 : BFI = 1 IF FR. Speech

C13 C14: SID ELSEBits C12 - C16 0 0 :SID = 0 C12: UFE

0 1 :SID = 1 0 :UFE=0 bad uplink frame 1 0 :SID = 2 1 : UFE=1 good up-link frame

Downlink Uplink Frame Error C15: TAF(UFE) C12 0 : TAF = 0(see subclause 4.8.3) 1 : TAF = 1 C13 - C15: spare

C16: Spare C16: SP 0 : SP = 0 1 : SP = 1

DTX indicator C17: DTXd C17: Spare0 : DTX not applied1 : DTX applied

Bits C18 - C21 Spare Spare


Data Bits (D-bits):

For Full Rate Speech:

Bits D1 .. D260: Speech block transferred in the same order as output from the transcoder (seeGSM 06.10).

For Enhanced Full Rate Speech:

The speech block is subdivided in five subsets. The order within a given subset is the same as outputfrom the transcoder (see ETS 300 726, GSM 06.60). Three parity bits are added at the end of each sub-set.

These parity bits are added to the bits of the subset, according to a degenerate (shortened) cyclic codeusing the generator polynomial:

g(D) = D3 + D + 1

The encoding of the cyclic code is performed in a systematic form which means that, in GF(2), thepolynomial:

d(m)Dn + d(m+1)Dn-1 + ......+ d(m + n-3)D3 + p(0)D2 + p(1)D + p(2)

where p(0), p(1), p(2) are the parity bits, when divided by g(D), yields a remainder equal to:

1 + D + D2

For every CRC, the transmission order is p(0) first followed by p(1) and p(2) successively.

Bit D1 : spare (binary "1").Bits D2...D39 : Indexes of the LSF submatrices.Bits D40...D42 : CRC over bits D1 to D22, D25 to D27 and D29.Bits D43...D95 : Indexes of the parameters of first sub-frame.Bits D96...D98 : CRC over bits D43 to D52, D91 and D92.Bits D99...D148 : Indexes of the parameters of second sub-frame.Bits D149...D151 : CRC over bits D99 to D103, D105, D144 and D145.Bits D152...D204 : Indexes of the parameters of third sub-frame.Bits D205...D207 : CRC over bits D152 to D161, D200 and D201.Bits D208...D257 : Indexes of the parameters of fourth sub-frame.Bits D258...D260 : CRC over bits D208 to D212, D214, D253 and D254.

Time Alignment Bits:

Bits T1 .. T4: Bits positioned at the end of the downlink frames. If the timing of the frame is tobe advanced 250 µS, these 4 bits are not transferred in order to reduce the framelength accordingly. When transferred the bits are set to binary "1".


3.5.1.2 Coding of Speech Frames for Adaptive Multi-Rate


Description Uplink Downlink

Frame type C1C2C3C4C5 C1C2C3C4C5(Bits C1 - C5) AMR: : 0 0 1 1 0 AMR: 0 0 1 1 0

Time Alignment(Bits C6 - C11)

The definition and coding is as for FR and EFR for all defined codes,except that some of the "not used" codes are defined in addition:C6C7C8C9C10C110 0 0 0 0 0 No change in frame timing . . . . . .1 0 1 0 0 0 Align_CMI_CMR (see 4.6.1.2.1) (*)1 0 1 0 0 1 Spare (*)1 0 1 0 1 0 Spare (*)1 0 1 0 1 1 Spare (*)(*): Command results in no change in frame timing.

Request or Indication Flag (RIF)(Bit C12)Typically RIF toggles every frame,exception see 4.6.1.2.1..

C12: RIF0 : This frame contains Codec_Mode_Indication1 : This frame contains Codec_Mode_Request

same meaning as in uplink

DTX indicator (DTXd) (uplink)Uplink Frame Error (UFE) (downlink)(Bit C13)

C13: DTXd0 : DTX not applied1 : DTX applied

C13: UFE0 : bad uplink frame1 : good uplink frame(see subclause 4.8.3)

Bits C14 - C15 Spare SpareCodec_Mode C16 C17 C18: same meaning as in uplink,(Bits C16, C17, C18): 0 0 0: Codec_Mode 4,75 kBit/s except that in every frame theThis field containseither theCodec_Mode_Request (RIF=1)or theCodec_Mode_Indication (RIF=0);see also notes 1 and 2.

0 0 1: Codec_Mode 5,15 kBit/s0 1 0: Codec_Mode 5,90 kBit/s0 1 1: Codec_Mode 6,70 kBit/s1 0 0: Codec_Mode 7,40 kBit/s1 0 1: Codec_Mode 7,95 kBit/s1 1 0: Codec_Mode 10,2 kBit/s1 1 1: Codec_Mode 12,2 kBit/s

Codec_Mode_Indication istransmitted, regardless of thevalue of the RIF.RIF indicates, however, theframes, in which the Codec_Modemay change (RIF=0)

Frame Classification(C19, C20, C21)(see GSM 06.93).

Rx_TypeC12..C140 0 0: Speech_Good0 0 1: Speech_Probably_Degraded0 1 0: Speech_Bad0 1 1: Spare1 0 0: SID_First1 0 1: SID_Update1 1 0: SID_Bad

Tx_TypeC12..C140 0 0: Speech0 0 1: spare0 1 0: spare0 1 1: Spare1 0 0: SID_First1 0 1: SID_Update1 1 0: spare

1 1 1: No_Data 1 1 1: No_DataBits C22 - C25 Spare Spare

Note 1: In TRAU frames the Codec_Mode_Request respectively the Codec_Mode_Indication are codedabsolutely (three bits for eight possible modes). Due to the limited bandwidth these parameters are codedwith two bits only on the radio interface, representing the (max.) four Codec_Modes of theActive_Codec_Set. The CCU performs the necessary transcoding.

Note 2: If the Frame Classification is set to "SID_Update", then always the Codec_Mode_Request istransmitted within the TRAU frame, regardless of the value of the RIF.


Data Bits (D-bits)

The following tables define the contents of the Data bits for all eight AMR Codec_Modes, in cases whenthe Frame Classification is either set to Speech_Good, or Speech_Probably_Degraded, or Speech_Bad.

The speech block is subdivided into four subsets. The order within a given subset is the same as outputfrom the transcoder (see GSM 06.90). The three parity bits added at the end of each subset aregenerated using the same cyclic code as defined for the Enhanced Full Rate.

Definition of D-Bits for AMR_Mode 12,2 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9a:Bits D1...D38: Indexes of the LSF submatrices (s1 to s38)Bits D39...D91: Indexes of the parameters of first sub-frame (s39 to s91)Bits D92...D94: CRC over bits s1 to s91.Bits D95...D144: Indexes of the parameters of second sub-frame (s92 to s141)Bits D145...D147: CRC over bits s92 to s141.Bits D148...D200: Indexes of the parameters of third sub-frame (s142 to s194)Bits D201...D203: CRC over bits s142 to s194.Bits D204...D253: Indexes of the parameters of fourth sub-frame (s195 to s244)Bits D254...D256: CRC over bits s195 to s244.The Downlink TRAU Frames in this Codec_Mode have the same layout as the uplink TRAU frames.

Definition of D-Bits for AMR_Mode 10,2 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9b:Bits D1...D26: Indexes of the LSF submatrices (s1 to s26)Bits D27...D72: Indexes of the parameters of first sub-frame (s27 to s72)Bits D73...D75: CRC over bits s1 to s72.Bits D76...D118: Indexes of the parameters of second sub-frame (s73 to s115)Bits D119...D121: CRC over bits s73 to s115.Bits D122...D167: Indexes of the parameters of third sub-frame (s116 to s161)Bits D168...D170: CRC over bits s116 to s161.Bits D171...D213: Indexes of the parameters of fourth sub-frame (s162 to s204)Bits D214...D216: CRC over bits s162 to s204Bits D217...D256: spare (40 bits); set to "1".For Downlink TRAU Frames in this Codec_Mode add 40 to all D-bit indices (D1->D41;D216->D256). All D-bits with indices 1 to 39 are spare and set to "1".

Definition of D-Bits for AMR_Mode 7,95 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9c:Bits D1...D27: Indexes of the LSF submatrices (s1 to s27)Bits D28...D61: Indexes of the parameters of first sub-frame (s28 to s61)Bits D62...D64: CRC over bits s1 to s61.Bits D65...D96: Indexes of the parameters of second sub-frame (s62 to s93)Bits D97...D99: CRC over bits s62 to s93.Bits D100...D133: Indexes of the parameters of third sub-frame (s94 to s127)Bits D134...D136: CRC over bits s94 to s127.Bits D137...D168: Indexes of the parameters of fourth sub-frame (s128 to s159)Bits D169...D171: CRC over bits s128 to s159Bits D172...D256: spare (85 bits); set to "1"For Downlink TRAU Frames in this Codec_Mode add 85 to D-bit indices (D1->D86;D171->D256). All D-bits with indices 1 to 85 are spare and set to "1".


Definition of D-Bits for AMR_Mode 7,40 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9d:Bits D1...D26: Indexes of the LSF submatrices (s1 to s26)Bits D27...D58: Indexes of the parameters of first sub-frame (s27 to s58)Bits D59...D61: CRC over bits s1 to s58.Bits D62...D90: Indexes of the parameters of second sub-frame (s59 to s87)Bits D91...D93: CRC over bits s59 to s87.Bits D94...D125: Indexes of the parameters of third sub-frame (s88 to s119)Bits D126...D128: CRC over bits s88 to s119.Bits D129...D157: Indexes of the parameters of fourth sub-frame (s120 to s148)Bits D158...D160: CRC over bits s120 to s148Bits D161...D256: spare (96 bits); set to "1"For Downlink TRAU Frames in this Codec_Mode add 96 to D-bit indices (D1->D97;D160->D256). All D-bits with indices 1 to 96 are spare and set to "1".

Definition of D-Bits for AMR_Mode 6,70 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9e:Bits D1...D26: Indexes of the LSF submatrices (s1 to s26)Bits D27...D55: Indexes of the parameters of first sub-frame (s27 to s55)Bits D56...D58: CRC over bits s1 to s55.Bits D59...D83: Indexes of the parameters of second sub-frame (s56 to s80)Bits D84...D86: CRC over bits s56 to s80.Bits D87...D115: Indexes of the parameters of third sub-frame (s81 to s109)Bits D116...D118: CRC over bits s81 to s109.Bits D119...D143: Indexes of the parameters of fourth sub-frame (s110 to s134)Bits D144...D146: CRC over bits s110 to s134Bits D147...D256: spare (110 bits); set to "1"For Downlink TRAU Frames in this Codec_Mode add 110 to D-bit indices (D1->D111;D146->D256). All D-bits with indices 1 to 110 are spare and set to "1".

Definition of D-Bits for AMR_Mode 5,90 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9f:Bits D1...D26: Indexes of the LSF submatrices (s1 to s26)Bits D27...D51: Indexes of the parameters of first sub-frame (s27 to s51)Bits D52...D54: CRC over bits s1 to s51.Bits D55...D75: Indexes of the parameters of second sub-frame (s52 to s72)Bits D76...D78: CRC over bits s52 to s72.Bits D79...D103: Indexes of the parameters of third sub-frame (s73 to s97)Bits D104...D106: CRC over bits s73 to s97.Bits D107...D127: Indexes of the parameters of fourth sub-frame (s98 to s118)Bits D128...D130: CRC over bits s98 to s118Bits D131...D256: spare (126 bits); set to "1"For Downlink TRAU Frames in this Codec_Mode add 126 to D-bit indices (D1->D127;D130->D256). All D-bits with indices 1 to 126 are spare and set to "1".

Definition of D-Bits for AMR_Mode 5,15 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9g:Bits D1...D23: Indexes of the LSF submatrices (s1 to s23)Bits D24...D46: Indexes of the parameters of first sub-frame (s24 to s46)Bits D47...D49: CRC over bits s1 to s46.Bits D50...D68: Indexes of the parameters of second sub-frame (s47 to s65)Bits D69...D71: CRC over bits s47 to s65.Bits D72...D90: Indexes of the parameters of third sub-frame (s66 to s84)Bits D91...D93: CRC over bits s66 to s84.Bits D94...D112: Indexes of the parameters of fourth sub-frame (s85 to s103)Bits D113...D115: CRC over bits s85 to s103Bits D116...D256: spare (141 bits); set to "1"For Downlink TRAU Frames in this Codec_Mode add 141 to D-bit indices (D1->D142;D115->D256). All D-bits with indices 1 to 141 are spare and set to "1".


Definition of D-Bits for AMR_Mode 4,75 kBit/s, uplink TRAU Frame, see GSM 06.90, table 9h:Bits D1...D23: Indexes of the LSF submatrices (s1 to s23)Bits D24...D48: Indexes of the parameters of first sub-frame (s24 to s48)Bits D49...D51: CRC over bits s1 to s48.Bits D52...D64: Indexes of the parameters of second sub-frame (s49 to s61)Bits D65...D67: CRC over bits s49 to s61.Bits D68...D88: Indexes of the parameters of third sub-frame (s62 to s82)Bits D89...D91: CRC over bits s62 to s82.Bits D92...D104: Indexes of the parameters of fourth sub-frame (s83 to s95)Bits D105...D107: CRC over bits s83 to s95Bits D108...D256: spare (149 bits); set to "1"For Downlink TRAU Frames in this Codec_Mode add 149 to D-bit indices (D1->D150;D107->D256). All D-bits with indices 1 to 149 are spare and set to "1".

The following tables define the contents of the Data bits for all eight AMR Codec_Modes, in cases whenthe Frame Classification is either set to SID_First, or SID_Update, or SID_Bad, or No_Data.The three parity bits added at the end of each subset are generated using the same cyclic code as definedfor the Enhanced Full Rate.

Definition of D-Bits for SID_First, uplink TRAU Frame:Bits D1 .. D35: set to "1".Bits D36 .. D38: CRC over bits D1 to D35.Bits D39 .. D256: spare (218 bits); set to "1".The Downlink TRAU Frame in this SID_First has the same layout as the uplink TRAU frame.

Definition of D-Bits for SID_Update and SID_Bad, uplink TRAU Frame, see GSM 06.92, table 1:Bits D1...D3: Moving average predictor, initial values (s1..s3)Bits D4...D29: Indexes of LSF submatrices (s4..s29)Bits D30...D35: Logarithmic frame energy (s30..s35)Bits D36...D38: CRC over bits s1 to s35.Bits D39...D256: spare (218 bits); set to "1"For the Downlink TRAU Frame in this SID_Update add 218 to D-bit indices (D1->D219;D38->D256). All D-bits with indices 1 to 218 are spare and set to "1".

Definition of D-Bits for No_Data, uplink TRAU Frame:Bits D1 .. D256: set to "1".The Downlink TRAU Frame in this No_Data has the same layout as the uplink TRAU frame.


Bits T1 .. T4: Bits positioned at the end of the downlink frames. If the timing of the frame is tobe advanced 250 µS, these 4 bits are not transferred in order to reduce the framelength accordingly. When transferred the bits are set to binary "1".


3.5.2 Coding of O&M FramesControl bits (C-bits):

Description Uplink DownlinkC1C2C3C4 C5 C1C2C3C4 C5

Frame type 0 0 1 0 1 : O&M 1 1 0 1 1 : O&M Bits C1 - C5 Bits C6 - C15 Spare Spare

Data Bits (D-bits):

Bits D1 .. D264:Bits used for transfer of O&M information. The coding and use of these bits are left to themanufacturer of the BSC/TRAU.

Spare Bits:

Bits S1 .. S6: Spare

3.5.3 Coding of Data FramesControl bits (C-bits):

Description Uplink DownlinkFrame type. C1C2C3C4 C5 C1C2C3C4 C5Bits C1 - C5 0 1 0 0 0 : Data 1 0 1 1 0 : Data

except 14,514.5 except 14,514.5

1 0 1 0 0 : Data14,514.51) 1 0 1 0 0 : Data 14,514.51)

Intermediate RA bit 0: 8 kbit/s 0: 8 kbit/srate. 1: 16 kbit/s 1: 16 kbit/sBit C6for data servicesexcept 14,514.5Spare Spare Sparefor Data 14,514.5Bits C7 - C15 Spare Spare

NOTE 1: The Data frame is in case of data 14,514.5 kbit/s used only for synchronization purposes. Thedata bits are in this case set according to subclause 4.5.1.

3.5.4 Coding of Extended Data FramesControl bits (C-bits):

Description Uplink DownlinkFrame type. C1C2C3C4 C5 C1C2C3C4 C5Bits C1 - C5 1 1 1 1 1 : 1 1 1 1 1 :

Extended Data Extended dataframe 14,514.5 kbit/s Frame 14,514.5

Bit C6Idle/Data/UFE Idle/data UFE

Frame indication


Multi Frame Structure M1, M2 M1, M2defined in GSM 04.21Bits M1, M2

3.5.5 Coding of Idle Speech FramesControl bits (C-bits):



Frame type. 1 0 0 0 0 : Idle Speech 0 1 1 1 0 : Idle SpeechBits C1 - C5

Bits C6 - C21 Coding as for FR and EFR Coding as for FR and EFRSpeech frames Speech frames

Note: Idle Speech Frames are not used in AMR, instead Frame Classification set to "No_Data" is applied.


Bits T1 .. T4: Coding as for Speech frames.

3.6. Order of Bit TransmissionThe order of bit transmission is:

The first octet is transferred first with the bit no. 1 first, bit no. 2 next etc.

4 Procedures4.1 Remote Control of Transcoders and Rate AdaptorsWhen the transcoder is positioned remote to the BTS, the Channel Codec Unit (CCU) in the BTS has tocontrol some of the functions in the remote Transcoder/Rate Adaptor Unit (TRAU) in the BSC.

This remote control is performed by inband signalling carried by the control bits (C-bits) in each TRAUframe.

The following functions in the TRAU are remotely controlled by the CCU:

- Shift between speech and data.- Control of the rate adaption functions for data calls.- Downlink frame timing for speech frames.- Transfer of DTX information.- Transfer of Codec_Mode_Request and Codec_Mode_Indication (AMR only)- Downlink Codec_Mode_Indication Time alignment (AMR only)

In addition, the inband signalling also provides means for transfer of O&M signals between the TRAU andthe BSC/BTS.

4.2 Resource AllocationAt reception of the ASSIGNMENT REQUEST message, e.g. at call setup, when a circuit switchedconnection is required, the BSC provides an appropriate TRAU to the circuit to be used between the BSCand the BTS and sends the CHANNEL ACTIVATION message to the BTS.

When receiving the CHANnel ACTIVation message, the BTS allocates the appropriate radio resourcesand a Channel Codec Unit (CCU) to be used.

In case of FR and EFR Speech or Data (except 14,514.5 kbit/s):

The CCU now starts sending uplink frames with the appropriate "Frame Type" and, for data calls, theintermediate rate adaption bit rate set.

When receiving the first frame, the TRAU sets the mode of operation accordingly and starts sendingdownlink frames with the "Frame Type" and, for data calls, the intermediate rate adaption bit rate set as anacknowledgement indication.


In case of Adaptive Multi-Rate speech:

The CCU starts sending uplink TRAU frames with the appropriate "Frame Type" and theCodec_Mode_Indication and Codec_Mode_Request set to "Initial_Codec_Mode". Consequently speechtransmission starts in uplink and downlink in the Initial_Codec_Mode. The CCU keeps the Codec_Mode inuplink and downlink fixed to the Initial_Codec_Mode until the correct time alignment of the Codec_Mode_Indication in downlink TRAU frames is achieved. Then the Codec Mode Adaptation may be enabled.

In case of Data 14,514.5 kbit/s:

The CCU starts sending uplink Data TRAU Frames with the appropriate "Frame Type" set to establish initialsynchronization.

When receiving the first frame, the TRAU sets the mode of operation accordingly and as anacknowledgement starts sending downlink Data TRAU Frames with the same “Frame Type”.

The CCU starts sending uplink Extended Data TRAU Frames with the appropriate "Frame Type" set uponreception of that acknowledge indication.

When receiving the first frame, when the "Frame Type" is set to Extended Data TRAU frame, the TRAU setsthe mode of operation accordingly and as an acknowledgement starts sending downlink Extended Data TRAUframes with the same “Frame Type”.

4.3 Resource ReleaseAt release of circuit switched resources, e.g. at call release, the connection between the CCU and theTRAU will be released by the BSC. The BSC has to indicate that the connection has been released. Howthis is performed is a BSC internal matter. However, three methods have been identified.

i) The BSC indicates the call release to the TRAU by inserting the PCM idle bit pattern described in GSM08.54 on the circuits towards the TRAU. The TRAU shall be able to detect this idle bit pattern. Whenreceived at the TRAU, the TRAU will loose frame synchronization and will start timer Tsync (seesubclausesection 4.8.2). If, when Tsync expires, the idle bit pattern has been detected, the TRAU shallterminate the operation (go idle) until a valid frame is again received.

ii) This alternative does not apply to Enhanced Full Rate and AMR Speech, Data 14,514.5 kbit/s case.

After a call release, the TRAU downlink channel is switched to the TRAU uplink channel (16 kbit/s side).

The TRAU shall be able to detect the looped downlink frame. When it is detected, the TRAU shall terminatethe normal operation (go idle) until a valid uplink TRAU frame is again received.

iii) It is handled by BSC internal signals (e.g. if the BSC and TRAU are collocated).

4.4 In Call ModificationIf the subscriber orders "In Call Modification", the CCU sets the "Frame Type" and, for data calls, the intermediate rate adaption bit rate in the uplink frames to the new mode of operation. When receiving thisinformation, the TRAU changes the mode of operation accordingly and sets the new "Frame Type" and,for data calls, the intermediate rate adaption bit rate in the downlink frames. The same procedure appliesfor mode change between Data 14,5 kbit/s.

In case of mode change to data 14,5 kbit/s from Speech or Data (other than 14,514.5 kbit/s) the sameprocedure as for “Resource Allocation” is performed.

4.5 Transfer of Idle FramesBetween the TRAU and the CCU a TRAU frame shall be transferred every 20 msS.

4.5.1 In Full rate data case:If no data is received from the MS (uplink direction) or no data is received from the MSC side of theinterface (downlink direction), idle data frames shall be transferred instead of data frames. Idle dataframes are data frames with all data bit positions set to binary "1". In addition, for 14,5 kbit/s channelcoding; the C6 bit shall be set to ‘1’ in the uplink extended data frame.


4.5.2 In Full rate speech case:If no speech is received from the MS (uplink direction), the CCU shall send TRAU speech frames with BFIflag set to 1 (bad frame) or idle speech frames.If no speech is received from the MSC side of the interface(downlink direction), idle speech frames shall be transferred instead of speech frames.

4.5.3 In Enhanced Full rate speech case:If no speech is received from the MS (uplink direction), the CCU shall send TRAU speech frames with BFIflag set to 1 (bad frame). If no speech is received from the MSC side of the interface (downlink direction),idle speech frames shall be transferred instead of speech frames.

4.5.4 In Adaptive Multi-Rate speech case:If no speech is received from the MS (uplink direction), the CCU shall send TRAU speech frames withCodec_Type set to "AMR", with Code_Mode_Indication set to the previously used Codec_Mode (or to theInitial_Codec_Mode, if at resource allocation) and with Rx_Type set to "No_Data".

If no speech is received from the MSC side (downlink direction), the TRAU shall send TRAU speechframes with Codec_Type set to "AMR", with Code_Mode_Indication set according to the receivedCodec_Mode_Request (or to the Initial_Codec_Mode, if at resource allocation) and with Tx_Type set to"No_Data".

4.6 Procedures for Speech Frames4.6.1 Time Alignment of Speech FramesThe time alignment needed for obtaining minimum buffer delay will differ from call to call. The reasons forthis are:

- The TRAUBSC will have no information about the radio timing at the BTS, and will start sending frames atan arbitrary or default time. Each TRAU frame is 320 bits (20 msS) and will in the worst case be received atthe BTS 319 bits out of phase.

- The different timeslots on one carrier is sent at different times (max 4.04 msS which equals 7 timeslots in aTDMA radio frame).

- Different channels may be transferred on different transmission systems using different routes in the network.The transmission delay may therefore differ.

The required time alignment between radio frames and TRAU frames is considered to be an internal BTSmatter for uplink frames. However, the buffer delay for these frames should be kept to a minimum.

For downlink frames, the procedures in the following sections should apply. In order to describe the timealignment procedure in the TRAU, two time alignment states are described (Initial Time Alignment stateand Static Time Alignment state).

In order to achieve optimum timing between the radio TDMA frames and the frames on the transmissionside, the speech coding and decoding function in the transcoder should not be synchronized.

4.6.1.1 Initial Time Alignment StateThe TRAU shall enter the Initial Time Alignment state at the switching-on of the system, when it goes idle(e.g. when receiving the PCM idle pattern after a call release as described in section 4.3), if loss of framesynchronization is detected, in call modification from data to speech is performed or if BSS internalhandover is detected.

In the Initial Time Alignmentinitial state, the frames shall only be delayed (or no change)(see note). Thetranscoder is able to adjust the time for transmitting the speech frames in steps of 125 µS (one speechsample). The CCU calculates the required timing adjustment and returns a frame including the number of250/500 µS steps by which the frames in the downlink direction have to be delayed (binary number in the"Time Alignment" field).

When receiving this information, the TRAU processes this data and sets the "Time Alignment" field in thenext downlink frame as ordered and then delays the subsequent frame accordingly.

NOTE: If the TRAU, in this state, receives an order to advance the next frame 250 µS, this order shallbe interpreted as "Delay frame 39*500 µS".


When a frame is delayed due to timing adjustments, the TRAU shall fill in the gap between the frameswith the appropriate number of binary "1".

After having adjusted the timing, the TRAU shall receive at least three new frames before a newadjustment is made. This in order to avoid oscillation in the regulation.

The TRAU shall change from the Initial Time Alignment state to the Static Time Alignment state when ithas performed two subsequent timing adjustments which are less than 500 µsS (including no change).

The procedure is illustrated in figure 4.1.

4.6.1.2 The Static Time Alignment StateIn the Static Time Alignment state, the TRAU performs timing adjustments in single steps of 250 µS. Thetiming may either be delayed (time alignment code 111110, advanced (time alignment code 111111) ornot changed (time alignment code 000000).

When receiving an order for adjusting the timing, the transcoder skips or repeats two speech samples inorder to achieve the correct timing.

If the timing is to be advanced 250 µS, the TRAU sets the "Time Alignment" field in the next downlinkframe as ordered and then the 4 last bits of the frame are not transferred (the T-bits).

If the timing is to be delayed, the TRAU sets the "Time Alignment" field in the next downlink frame asordered and then delays the subsequent frame by adding four binary "1" between the frames.

After having adjusted the timing, the TRAU shall receive at least three new frames before a newadjustment is made.

If, in this state, the TRAU detects a change in the timing of the uplink frames bigger than n x 250 µS,where n = 4, it shall enter the Initial Time Alignment state and in that state it may perform an adjustmenton the downlink equal to the change detected on the uplink.

4.6.1.2.1 Time Alignment of Codec_Mode_Indication for AMRIn the Static Time Alignment state for Adaptive Multi-Rate speech it might still be necessary to align thephase of the Codec_Mode_Indication and Codec_Mode_Request as indicated in downlink TRAU framesby the RIF bit, in order to minimise the transmission delay in downlink direction.

If the phase is correct, i.e. the TRAU frames marked with RIF set to 0 are received in time for thetransmission in even speech frames on the radio interface, then no action is needed, see GSM 05.09.

If the phase is not correct, then the CCU shall send one "Align_CMI_CMR" command uplink. The TRAUshall send two consecutive TRAU frames with Codec_Mode_Indication (RIF set to 0 two times) and bythis shall invert the phase of Codec_Mode_Indication and Codec_Mode_Request in downlink.



4.6.1.3 Initiation at Resource AllocationWhen the BTS receives the CHANNEL ACTIVATION message from the BSC, it allocates the appropriateradio resources and a Channel Codec Unit (CCU). In case of AMR speech the BSC provides the BTS withthe necessary information on AMR operation parameters, especially the Active_Codec_Set and theInitial_Codec_Mode, see GSM 08.58. The CCU then initiates sending of speech frames (or idle speechframes if speech is not received from the MS) towards the transcoder with normal frame phase for theTDMA channel in question. The "Time Alignment" field in these frames is set to "no change".

The TRAU will now be in the Initial Time Alignment state. When receiving the first frame it shall startsending speech frames (or idle speech frames) towards the BTS with arbitrary or default phase related tothe uplink frame phase.

When receiving these frames the CCU calculates the timing adjustment required in order to achieveminimum buffer delay and sets the "Time Alignment" field in the uplink frames accordingly.

The procedures described for the Initial and for the Static Time Alignment states are then followed duringthe call.

4.6.1.4 Time Alignment During Handover4.6.1.4.1 BSS External HandoverFor BSS external handover, the procedure described in section 4.6.1.3 should be used by the newBSC/BTS at resource allocation.

4.6.1.4.2 BSS Internal HandoverIf a BSS internal handover has been performed, the timing of the downlink frames may have to beadjusted several steps of 250/500 µS. In order to speed up the alignment of the downlink frames, thismust be detected by the TRAU, e.g. by detecting the change in the uplink frame timing as described insection 4.6.1.2. The TRAU should then enter the Initial Time Alignment state and in that state it mayperform an adjustment on the downlink equal to the change detected on the uplink.

4.6.2 Procedures for Discontinuous Transmission (DTX)The procedures for comfort noise are described in GSM 06.12, for Full rate speech and in GSM 06.62(ETS 300 728) for Enhanced Full rate speech, the overall operation of DTX is described in GSM 06.31and in GSM 06.81 (ETS 300 729) for respectively Full rate speech and Enhanced Full rate speech andthe Voice Activity Detector is described in GSM 06.32 and GSM 06.82 (ETS 300 730) for respectively Fullrate speech and Enhanced full rate speech. The relevant procedures for Adaptive Multi-Rate speech aredescribed in GSM 06.92, GSM 06.93 and GSM 06.94.

The DTX Handler function is considered as a part of the TRAU when remote transcoders are applied. Thespecification of the DTX Handler is given in GSM 06.31 for Full rate speech, and in GSM 06.81(ETS 300 729) for Enhanced Full Rate speech and GSM 06.93 for Adaptive Multi-Rate speech..

4.6.2.1 DTX procedures in the uplink directionIn all frames in the uplink direction, the BFI (Bad Frame Indicator), the SID (Silence Descriptor) indicatorand the TAF (Time Alignment Flag) indicator is set as output from the RSS (see GSM 06.31 and GSM06.81 (ETS 300 729)) in case of the Full Rate and Enhanced Full Rate speech.

In the comfort noise states, the MS will transmit a new frame only every 480 msmS (24 frames). Theseframes are transferred in the normal way between the CCU and the TRAU. Between these frames theCCU shall transfer uplink idle speech frames in case of Full Rate Speech and speech frames with BFI setto "1" in case of Enhanced Full rate Speech.

In case of the Adaptive Multi-Rate speech all frames are classified by the Rx_Type, see GSM 06.93.

4.6.2.2 DTX procedures in the downlink directionTo inform the DTX handler in the remote transcoder whether downlink DTX may be applied or not, theDTXd bit (C17) in the uplink speech frame is used. The coding is as follows:

DTXd = 0 : downlink DTX is not applied;DTXd = 1 : downlink DTX is applied.


Though this parameter is linked with the resource allocation in the BTS at call setup, its value may varyduring the connection.

In the downlink frames the SP (Speech) indicator is set as output from the TX DTX handler (seeGSM 06.31 and GSM 06.81 (ETS 300 729)) in case of Full Rate speech and Enhanced Full Rate speech.

If downlink DTX is not used, the SP indicator should be coded binary "1".

In case of the Adaptive Multi-Rate speech all frames are classified by the Tx_Type, see GSM 06.93.

4.7 Procedures for Data Frames4.7.1 9.6 and 4.8 kbit/s channel codingWhen rate adaption to 64 Kbit/s is performed at the BTS (sub-64 kbit/s traffic channels are not used), therate adaption between the format used on the radio interface and the 64 Kbit/s format is made by theRA1/RA1' and the RA2 function as described in GSM. 08.20. This is illustrated in figure 4.2.

•••••••• ••••••••••••••• •••• RA2 •••••••••••••• RA1 • RA1' ••••••••• • •••••••• • ••••••••••••••• • 64 Kbit/s CCITT V.110 Channel 80 bits codec frame frame

Figure GSM 08.60/4.2: Rate adaption when performed at the BTS.When sub-64 kbit/s traffic channels are used, up to four data frames are transferred in each TRAU frame.In order to convert between the TRAU frame format and the CCITT 80 bits frame format an additionalintermediate rate adaption function, RAA, is applied. This is illustrated in figure 4.3.

•••••••• ••••• Abis ••••• ••••••••••• •••• RA2 ••••••••••RAA•••••••••RAA••••• RA1•RA1'•••••• • •••••••• • ••••• • ••••• • ••••••••••• • 64 Kbit/s CCITT TRAU CCITT Channel V.110 4 X 72 + 32 V.110 codec 80 bits bits 80 bits frame frame frame frame

Figure GSM 08.60/4.3: Rate adaption when 16 kbit/s traffic channels are used4.7.1.1 The RAA FunctionThe RAA function is used to convert between the CCITT V.110 80 bits frame format and the TRAU frameformat. When going from the V.110 format to the TRAU frame format the first octet (all bits codedbinary "0") in the CCITT V.110 80 bits frame is stripped off. Up to four such frames are then transferred ineach TRAU frame as shown in section 3.3.

When going from the TRAU frame format to the V.110 format the data frames are separated and thesynchronization octet (all bits coded binary "0") is again included.

The 80 bits V.110 frame is illustrated in figure 4.4, and the modified 72 bits frame is illustrated infigure 4.5.


Bit number Octet no. 1 2 3 4 5 6 7 8

0 0 0 0 0 0 0 0 01 1 D1 X X X X X X2 1 X X X X X X X3 1 X X X X X X X4 1 X X X X X X X5 1 X X X X X X X6 1 X X X X X X X7 1 X X X X X X X8 1 X X X X X X X9 1 X X X X X X X

Figure GSM 08.60/4.4: CCITT V.110 80 bits frame

Bit numberOctet no. 1 2 3 4 5 6 7 8

0 1 D1 X X X X X X1 1 X X X X X X X2 1 X X X X X X X3 1 X X X X X X X4 1 X X X X X X X5 1 X X X X X X X6 1 X X X X X X X7 1 X X X X X X X8 1 X X X X X X X

Figure GSM 08.60/4.5: Modified CCITT V.110 72 bits frame transferredin a TRAU data frame position

4.7.1.2 The RA1/RA1' FunctionThis function is described in GSM 04.21.

4.7.1.3 The RA2 FunctionThis function is described in GSM 04.21.

4.7.1.4 Procedures for 8 kbit/s intermediate rate adaption rateFor 8 kbit/s intermediate rate adaption rate up to two data frames are transferred in each TRAU frame.The first data frame is transferred in TRAU data frame position 1 and the subsequent data frame istransferred in TRAU data frame position 3 (see section 3.3).

In TRAU data frame position 2 and 4, all bits are coded binary "1".

If the data transfer terminates before the TRAU frame has been completed, the remaining data bitpositions in the TRAU frame should be coded binary "1".

4.7.1.5 Procedures for 16 kbit/s intermediate rate adaption rateFor 16 kbit/s intermediate rate adaption rate, up to four data frames are transferred in each TRAU frame.The first data frame is transferred in TRAU data frame position 1, the next in data frame position 2 etc.

If the data transfer terminates before the TRAU frame has been completed, the remaining data bitpositions in the TRAU frame should be coded binary "1".

4.7.1.6 Support of Non-Transparent Bearer ApplicationsIn GSM 08.20, the procedures for transfer of non-transparent bearer applications are specified. The 240bit RLP frame is converted to four modified V.110 80 bit frames.

The same conversion is applied when transferred in a TRAU frame. The frames are coded as specified insections 4.7.4 and 4.7.5.


4.7.2 14,514.5 kbit/s channel codingWhen rate adaption to 64 Kbit/s is performed at the BTS (sub-64 kbit/s traffic channels are not used), therate adaption between the format used on the radio interface and the 64 Kbit/s format is as described inGSM 08.20.

When sub-64 kbit/s traffic channels are used, up to eight 36 bits frames are transferred in each E-TRAUframe. In order to convert between the E-TRAU frame format and the 36 bits frame format used for theradio interface an additional intermediate rate adaption function, RA1’/RAA’, is applied. This is illustratedin figure 4.3.1 (see also GSM 08.20).

•••••••• •••••• Abis •••••••••••• •••• RA2 ••••••••••RAA'•••••••••••••••• RAA'•RA1'•••••• • •••••••• • •••••• • •••••••••••• • 64 Kbit/s A-TRAU E-TRAU Radio 8 X 36 + 32 320 Interface bits bits frame frame frame

Figure GSM 08.60/4.3.1: Rate adaption when 16 kbit/s traffic channels are used4.7.2.1 The RAA’ FunctionSee GSM 08.20

4.7.2.2 The RA1’/RAA' FunctionThis function is described in GSM 08.20.

4.7.2.3 The RA2 FunctionThis function is described in GSM 04.21.

4.8 Frame Synchronization4.8.1 Search for Frame SynchronizationThe frame synchronization is obtained by means of the first two octets in each frame, with all bits codedbinary "0", and the first bit in octet no. 2, 4, 6, 8, ... 38 coded binary "1". The following 35 bit alignmentpattern is used to achieve frame synchronization:

00000000 00000000 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX

4.8.2 Frame Synchronization After Performing Downlink Timing AdjustmentsIf the timing of the downlink speech frames is adjusted, the adjustment is indicated in bits C6 - C11 asdescribed in sections 4.6.1.1 and 4.6.1.2. The frame synchronization unit shall change its framesynchronization window accordingly.


4.8.3 Frame Synchronization Monitoring and RecoveryThe monitoring of the frame synchronization shall be a continuous process.

Loss of frame synchronization shall not be assumed unless at least three consecutive frames, each withat least one framing bit error, are detected.

In case of Full Rate speech:

If the TRAU looses its frame synchronization it starts a timer Tsync = 1 second. If Tsync expires beforeframe synchronization is again obtained the TRAU initiates sending of the urgent alarm pattern described insection 4.10.2.

The exception from this procedure is when "Resource Release" is detected while Tsync is running (seesection 4.3). In this case, the procedure in section 4.3 shall be followed.

If loss of frame synchronization is detected by the CCU it starts a timer Tsync. If Tsync expires before framesynchronization is again obtained the call shall be released and an indication given to O&M.

Tsync is reset every time frame synchronization is again obtained.

In case of Enhanced full rate and Adaptive Multi-Rate speech:

When it detects a framing bit error, the TRAU uses the control bit UFE (uplink Frame Error) in the nextdownlink TRAU frame to indicate it to the CCU. When the CCU receives a TRAU frame indicating anUplink Frame Error and which has no errors on the sychronization pattern and the control bits, it starts a timerTsyncU.

If loss of frame sychronization is detected by the CCU it starts a timer TsyncD. If TsyncD or TsyncU expiresbefore frame sychronization is again obtained, the call shall be released as specified in GSM 08.58 with thecase field set to " Remote Transcoder Failure".

TsyncD is reset every time frame synchronisation is again obtained.

TsychU is reset every time three consecutive TRAU frames are received without Uplink Frame Errorindication, without errors on the frame synchronisation pattern and on the control bits.

TsyncD and TsyncU are parameters set by O&M (default value = 1 second).

In case of Data 14,514.5 kbit/s:

The following 17 bit alignment pattern of the Extended Data TRAU Frame is used for Frame SynchronizationMonitoring:

00000000 00000000 1XXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX

When it detects a framing bit error, the TRAU uses the control bit UFE (uplink Frame Error) in the nextdownlink Extended Data TRAU Frame to indicate it to the CCU. When the CCU receives an Extended DataTRAU Frame indicating an Uplink Frame Error and which has no errors on the synchronization pattern andthe control bits, it starts a timer TsyncU and TsyncR.

If loss of frame synchronization is detected by the CCU it starts a timer TsyncD and starts sending DataTRAU Frames in the uplink direction to trigger the TRAU to start sending Data TRAU Frames in thedownlink direction to be used for downlink Synchronization Recovery.

If TsyncR expires before frame synchronization is again obtained, the CCU starts sending Data TRAUFrames in the uplink direction to be used for uplink Synchronization Recovery.

If TsyncD or TsyncU expires before frame synchronization is again obtained, the call shall be released asspecified in GSM 08.58 with the case field set to " Remote Transcoder Failure".


TsyncD is reset every time frame synchronization is again obtained.

TsychU and TsyncR is reset every time three consecutive TRAU frames are received without Uplink FrameError indication, without errors on the frame synchronization pattern and on the control bits.

TsyncD and TsyncU are parameters set by O&M (default value = 1 second)

TsyncR are a parameter set by O&M (default value = 60 milliseconds).

4.9 Correction/detection of bit errors on the terrestrial circuits4.9.1 Error Detection on the Control BitsFor the control bits, (C-bits), no error coding is made. However, in order to reduce the possibility ofmisinterpretation of control information due to bit errors, the following procedure should be followed.

4.9.1.1 General ProcedureIf any undefined combination of the C-bits is received (see section 3.5), the frame should be reacted uponas received with errors.

4.9.1.2 Speech FramesIn addition to the general procedure described in the previous section, the following procedure should befollowed for the speech frames:

Bits C6 - C11: Time Alignment.

The full range of the time alignment adjustment should only be applied when the TRAU is in the InitialTime Alignment state (see sections 4.6.1.1 and 4.6.1.2).

If, in the Static Time Alignment state, a time alignment order is received indicating an adjustment of morethan 250 µS, the next downlink frame should be delayed only one 250 µS step.

If an uplink frame is received with the "Time Alignment" field set to an unused value (101000 ... 111101 incase of FR and EFR; 101001 … 111101 in case of AMR), this value should be interpreted as "no change".

4.9.2 Handling of frames received with errorsIf TRAU frame is received in the uplink or downlink with detectable errors in the control bits, then thecontrol information shall be ignored. The speech or data bits shall be handled as if no error had beendetected.

If frame synchronisation has been lost (see section 4.8.3) in the uplink direction the TRAU shall:

- for speech, mute the decoded speech as if it has received frames with errors (cf. GSM 06.11 and GSM 06.61(ETS 300 727) and GSM 06.91);

- for data, send idle frames as defined in GSM 08.20 to the MSC/interworking.

4.9.2.1 In case of Full Rate:If frame synchronisation has been lost in the downlink direction then the same procedure shall be followedas when frame synchronisation is lost on the PCM link.

4.9.2.2 In case of Enhanced Full rate and Adaptive Multi-Rate:For speech calls, the CCU shall transmit a layer two fill frame on the air interface if frame synchronizationhas been lost in the downlink direction.

If a CRC error is detected in a downlink TRAU speech frame a solution can be to transmit a layer two fillframe on the air interface, another solution can be to replace the bad part of the TRAU speech frame only.The choice of the solution is left open.

If a CRC error is detected in a uplink TRAU speech frame, the TRAU speech frame shall be regarded asbad or partly bad and the TRAU shall apply the procedure defined in GSM 06.61 (ETS 300 727),respectively GSM 06.91..


4.10 Procedures for Operation & MaintenanceThe general procedures for Operation and Maintenance are described in GSM 12.21.

If the transcoders are positioned outside the BTS, some O&M functions will be required for the TRAU andthe CCU. In particular this applies for transcoders positioned at the MSC site.

The transcoders outside the BTS are considered a part of the BSC, and the O&M functions for the TRAUshould therefore be implemented in the BSC.

The CCU is a part of the BTS and the O&M functions for this unit should therefore be implemented in theBTS.

4.10.1 Transfer of O&M Information Between the TRAU and the BSCThe transfer of O&M information between the BSC and the TRAU is possible to do in two ways. Either it ishandled directly between the BSC and the TRAU or a BTS is used as a message transfer point. Thechoice between the two methods is up to the manufacturer of the BSC:

i) The transfer of O&M information between the BSC and the TRAU is handled internally by the BSC. TheO&M signalling between the TRAU and the BSC may either be handled by proprietary BSC solutions or theO&M TRAU frames defined in sections 3.2 and 3.5.2 could be used. In the latter case, the BSC has to act as aterminal for the O&M TRAU frames sent between the TRAU and the BSC.

ii) The O&M information between the TRAU and the BSC is transferred using O&M TRAU frames between theTRAU and the CCU in a BTS. The BTS then acts as a relay function between the O&M TRAU frames andthe associated O&M messages sent between the BTS and the BSC.

4.10.2 Procedures in the TRAUIn case of urgent fault conditions in the TRAU, e.g. loss of frame synchronization, non-ability of thetranscoder to process data etc., this should if possible, be signalled to the BTS/BSC as an urgent alarmpattern. The urgent alarm pattern is a continuous stream of binary "0".

If O&M TRAU frames information between the TRAU and the BSC is transferred using O&M framesbetween the CCU in a BTS and the TRAU, the TRAU sends O&M frames periodically until the identicalO&M TRAU frame is received for acknowledgement. The period is at least 64*20ms (1,28 sec).

In case of minor fault conditions, when no immediate action is required, the TRAU may send O&M framesindicating the fault instead of the urgent alarm pattern.

4.10.3 Procedures in the BSCThe BSC should be able to detect a faulty TRAU, take it out of service and give an indication to O&M. Afaulty TRAU could be detected e.g. by routine tests, alarms from the TRAU, release of call initiated by theBTS due to remote transcoder failure etc. How this is handled by the BSC is regarded as a BSC internalmatter.

4.10.3.1 Use of O&M FramesThe use and coding of O&M TRAU frames is left to the implementor of the BSC/TRAU.

If O&M TRAU frames are used, they are always carrying 264 data bits.

Any corresponding O&M message between the BSC and the BTS shall always carry all 264 O&M databits.

4.10.4 Procedures in the BTSIf a CCU in a BTS receives O&M TRAU frames from the TRAU, the BTS shall:

- send the identical frame to the TRAU for acknowledgement; and

- put the 264 data bits from the received frames into an appropriate O&M message and send it to the BSC.

If the CCU receives O&M frames during a call then "stolen frames" shall be indicated to the MS and layer2 frames of format A (see GSM 04.06) shall be transmitted.


If the CCU receives O&M frames during a data call, then the same procedure shall be used as whenV.110 frame is lost.

If receiving an O&M message from the BSC, carrying TRAU O&M information, the BTS puts the 264 databits from the received message into an O&M TRAU frame and then the CCU allocated to the addressedconnection sends the frame to the TRAU in one single O&M TRAU frame. Repetition is done according toGSM 12.21.

In case of a faulty CCU, the O&M procedures are BTS internal.

If the CCU receives the urgent alarm pattern, the BTS shall initiate release of the call as specified in GSM08.58 with the cause field set to "Remote Transcoder Failure".


History

Document history

March 1996 Public Enquiry PE 104: 1996-03-25 to 1996-08-16

November 1996 Vote V 115: 1996-11-25 to 1997-01-17

March 1997 First Edition

September 1997 One-step Approval Procedure OAP 9803: 1997-09-19 to 1998-01-16(Second Edition)

February 1998 Second Edition

January 1999 Introduction of AMR; Source: Ericsson, Nokia, Siemens

January 1999 After discussion in SMG11 / TFO subgroup and SMG2 drafting group; Source: SMG2 DG

ISBN 2-7437-2001-8Dépôt légal : Février 1998

ETSI SMG2 WPB Tdoc SMG2 169/99Sophia Antipolis11-15 January 1999

CHANGE REQUEST No : A008_rev2B

Please see embedded help file at the bottom of thispage for instructions on how to fill in this form correctly.

Technical Specification GSM / UMTS: 08.60 Version 5.1.1

Submitted to SMG #28 for approval without presentation ("non-strategic")Xlist plenary meeting or STC here ↑ for information X With presentation ("strategic")

PT SMG CR cover form. Filename: crf26_3.doc

Proposed change affects: SIM ME Network X(at least one should be marked with an X)

Work item: AMR

Source: SMG2 drafting group Date: 27/01/99

Subject: Introduction of the AMR

Category: F Correction Release: Phase 2A Corresponds to a correction in an earlier release Release 96

(one category B Addition of feature X Release 97and one release C Functional modification of feature Release 98 Xonly shall be D Editorial modification Release 99marked with an X) UMTS

Reason forchange:

Support of the AMR

Clauses affected:

Other specs Other releases of same spec → List of CRs:affected: Other core specifications → List of CRs:

MS test specifications / TBRs → List of CRs:BSS test specifications → List of CRs:O&M specifications → List of CRs:

Othercomments:

Proposal B. See proposal A in Tdoc SMG2 99-168.Proposal B was first presented to SMG2 WPB in Tdoc SMG2 WPB 99-101, then revised andproposed a first time to SMG2 in Tdoc SMG2 99-138

EUROPEAN ETS 300 737

TELECOMMUNICATION JanuaryFebruary 19998

STANDARD Second Edition

Source: SMG Reference: RE/SMG-020860QR1

ICS: 33.020

Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)

GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS

R

Digital cellular telecommunications system (Phase 2+);Inband control of remote transcoders and rate adaptors for

Enhanced Full Rate (EFR) and f Full r Rate (FR) traffic channels(GSM 08.60 version 7.0.0 5.1.1 )

ETSI

European Telecommunications Standards Institute

ETSI Secretariat

Postal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [email protected]

Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16

Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the foregoingrestriction extend to reproduction in all media.

© European Telecommunications Standards Institute 1998. All rights reserved.

Page 3ETS 300 737 (GSM 08.60 version 7.0.05.1.1): JanuaryFebruary 19998

Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to "ETSI Editingand Committee Support Dept." at the address shown on the title page.

Page 4ETS 300 737 (GSM 08.60 version 7.0.05.1.1): February January 19981999

Contents

Foreword ....................................................................................................................................................................... 6

1 Scope.................................................................................................................................................................. 81.1 Normative references ........................................................................................................................ 81.2 Abbreviations .................................................................................................................................... 9

2 General Approach .............................................................................................................................................. 9

3 Frame Structure................................................................................................................................................ 12Speech Frames ................................................................................................................................................. 12

3.1.1 TRAU format (for FR and EFR)............................................................................... 123.1.2 B-TRAU format (for AMR)...................................................................................... 13

3. O&M Frames .................................................................................................................................. 143.3 Data Frames .................................................................................................................................... 15

3.3.1 Data Frame (for Synchronisation)............................................................................. 153.3.2 Extended data frame (E-TRAU : data transport) ...................................................... 16

3. Idle Speech Frames ......................................................................................................................... 173.5 Coding............................................................................................................................................. 17

3.5.1 Coding of Speech Frames ......................................................................................... 183.5.1.1 TRAU format (for FR and EFR)................................................... 183.5.1.2 B-TRAU format (for AMR) ......................................................... 20

3.5.2 Coding of O&M Frames ........................................................................................... 253.5.3 Coding of Data Frames ............................................................................................. 253.5.4 Coding of Extended Data Frames ............................................................................. 253.5.5 Coding of Idle Speech Frames.................................................................................. 25

3.6 Order of Bit Transmission............................................................................................................... 263.7 Framing Pattern Substitution in B-TRAU frame............................................................................. 26

3.7.1 FPS encoding............................................................................................................ 26

4 Procedures........................................................................................................................................................ 284.1 Remote Control of Transcoders and Rate Adaptors........................................................................ 284.2 Resource Allocation ........................................................................................................................ 284.3 Resource Release ............................................................................................................................ 284.4 In Call Modification........................................................................................................................ 294.5 Transfer of Idle Frames................................................................................................................... 29

4.5.1 In Full rate data case:................................................................................................ 294.5.2 In Full rate speech case:............................................................................................ 294.5.3 In Enhanced Full rate speech case: ........................................................................... 294.5.4 In Adaptive Multi-Rate speech case: ........................................................................ 29

4.6 Procedures for Speech Frames ........................................................................................................ 294.6.1 Time Alignment of Speech Frames........................................................................... 29

4.6.1.1 Initial Time Alignment State ........................................................ 304.6.1.2 The Static Time Alignment State.................................................. 304.6.1.3 Time Alignment of Codec_Mode_Indication for AMR ............... 324.6.1.4 Initiation at Resource Allocation .................................................. 324.6.1.5 Time Alignment During Handover ............................................... 32

4.6.1.5.1 BSS External Handover .............................. 324.6.1.5.2 BSS Internal Handover ............................... 32

4.6.2 Procedures for Discontinuous Transmission (DTX)................................................. 324.6.2.1 DTX procedures in the uplink direction ....................................... 324.6.2.2 DTX procedures in the downlink direction .................................. 33

4.7 Procedures for Data Frames ............................................................................................................ 334.7.1 9.6 and 4.8 kbit/s channel coding.................................................................................................... 33

4.7.1.1 The RAA Function.................................................................................................... 334.7.1.2 The RA1/RA1' Function ........................................................................................... 34


4.7.1.3 The RA2 Function.....................................................................................................344.7.1.4 Procedures for 8 kbit/s intermediate rate adaption rate.............................................344.7.1.5 Procedures for 16 kbit/s intermediate rate adaption rate...........................................344.7.1.6 Support of Non-Transparent Bearer Applications ....................................................34

4.7.2 14.5 kbit/s channel coding...............................................................................................................354.7.2.1 The RAA’ Function ..................................................................................................354.7.2.2 The RA1’/RAA' Function .........................................................................................354.7.2.3 The RA2 Function.....................................................................................................35

4.8 Frame Synchronization....................................................................................................................354.8.1 Search for Frame Synchronization............................................................................354.8.2 Frame Synchronization After Performing Downlink Timing Adjustments...............354.8.3 Frame Synchronization Monitoring and Recovery ...................................................36

4.9 Correction/detection of bit errors on the terrestrial circuits.............................................................374.9.1 Error Detection on the Control Bits ..........................................................................37

4.9.1.1 General Procedure ........................................................................374.9.1.2 Speech Frames..............................................................................37

4.9.2 Handling of frames received with errors...................................................................374.9.2.1 In case of Full Rate: ......................................................................374.9.2.2 In case of Enhanced Full rate and Adaptive Multi-Rate : .............37

4.10 Procedures for Operation & Maintenance .......................................................................................384.10.1 Transfer of O&M Information Between the TRAU and the BSC.............................384.10.2 Procedures in the TRAU...........................................................................................384.10.3 Procedures in the BSC ..............................................................................................38

4.10.3.1 Use of O&M Frames.....................................................................384.10.4 Procedures in the BTS ..............................................................................................38


Foreword

This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group (SMG) of theEuropean Telecommunications Standards Institute (ETSI).This ETS specifies the inband control of remote transcoders and rate adaptors for full rate speech, Enhanced Fullrate speech, Adaptive Multi-Rate speech in full rate channel mode and full rate data within the Digital cellulartelecommunications system (Phase 2+).The specification from which this ETS has been derived was originally based on CEPT documentation, hence thepresentation of this ETS may not be entirely in accordance with the ETSI/PNE Rules.

Transposition dates

Date of adoption of this ETS: 23 January 1998

Date of latest announcement of this ETS (doa): 31 May 1998

Date of latest publication of new National Standardor endorsement of this ETS (dop/e): 30 November 1998

Date of withdrawal of any conflicting National Standard (dow): 30 November 1998


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1 Scope

When 64 kbit/s traffic channels are used on the Abis interface, the speech shall be coded according to CCITTRecommendation G.711 and the data rate adaptation shall be as specified in GSM 04.21 and GSM 08.20.In the case where 16 kbit/s traffic channels are used for full rate speech or enhanced full rate speech or adaptativemulti-rate speech or full rate data service, then this specification shall apply for frame structure and for control ofremote transcoders and additional rate adaptors.The use and general aspects of the Abis interface are given in GSM 08.51.

NOTE: This specification should be considered together with the GSM 06 series of specifications,GSM 04.21 (Rate Adaptation on the MS-BSS Interface) and GSM 08.20 (Rate Adaptation onthe BS/MSC Interface).

1.1 Normative references

This ETS incorporates by dated and undated reference, provisions from other publications. These normativereferences are cited at the appropriate places in the text and the publications are listed hereafter. For datedreferences, subsequent amendments to or revisions of any of these publications apply to this ETS only whenincorporated in it by amendment or revision. For undated references, the latest edition of the publication referred toapplies.[1] GSM 01.04 (ETR 350): "Digital cellular telecommunications system (Phase 2+);

Abbreviations and acronyms".

[2] GSM 04.06 (ETS 300 938): "Digital cellular telecommunications system; MobileStation - Base Station System (MS - BSS) interface; Data Link (DL) layerspecification".

[3] GSM 04.21 (ETS 300 945): "Digital cellular telecommunications system; Rate adaptionon the Mobile Station - Base Station System (MS - BSS) interface".

[4] GSM 06.01 (ETS 300 960): "Digital cellular telecommunications system; Full ratespeech; Processing functions".

[5] GSM 06.10 (ETS 300 961): "Digital cellular telecommunications system; Full ratespeech; Transcoding".

[6] GSM 06.11 (ETS 300 962): "Digital cellular telecommunications system; Full ratespeech; Substitution and muting of lost frames for full rate speech channels".

[7] GSM 06.12 (ETS 300 963): "Digital cellular telecommunications system; Full ratespeech; Comfort noise aspect for full rate speech traffic channels".

[8] GSM 06.31 (ETS 300 964): "Digital cellular telecommunications system; Full ratespeech; Discontinuous Transmission (DTX) for full rate speech traffic channels".

[9] GSM 06.32 (ETS 300 965): "Digital cellular telecommunications system; VoiceActivity Detector (VAD)".

[10] GSM 08.20: "Digital cellular telecommunications system; Rate adaption on the BaseStation System - Mobile-services Switching Centre (BSS - MSC) interface".

[11] GSM 08.51: "Digital cellular telecommunications system; Base Station Controller -Base Transceiver Station (BSC - BTS) interface; General aspects".

[12] GSM 08.54: "Digital cellular telecommunications system (Phase 2+); Base StationController - Base Transceiver Station (BSC - BTS) interface; Layer 1 structure ofphysical circuits".

[13] GSM 08.58: "Digital cellular telecommunications system (Phase 2+); Base StationController - Base Transceiver Station (BSC - BTS) interface; Layer 3 specification".

[14] GSM 12.21 (ETS 300 623): "Digital cellular telecommunications system (Phase 2);Network Management (NM) procedures and message on the A-bis interface".

[15] CCITT Recommendation G.711: "Pulse code modulation (PCM) of voice frequencies".

[16] CCITT Recommendation I.460: "Multiplexing, rate adaption and support of existinginterfaces".


[17] CCITT Recommendation V.110: "Support of data terminal equipments (DTEs) with V-Series interfaces by an integrated services digital network".

[18] GSM 06.51 (ETS 300 723): "Digital cellular telecommunications system; Enhanced Fullrate speech processing functions".

[19] GSM 06.60 (ETS 300 726): "Digital cellular telecommunications system; Enhanced Fullrate speech transcoding".

[20] GSM 06.61 (ETS 300 727): "Digital cellular telecommunications system; Substitutionand muting of lost frames for Enhanced Full rate speech channels".

[21] GSM 06.62 (ETS 300 728): "Digital cellular telecommunications system; Comfort noiseaspect for Enhanced Full rate speech traffic channels".

[22] GSM 06.81 (ETS 300 729): "Digital cellular telecommunications system; DiscontinuousTransmission (DTX) for Enhanced Full rate speech traffic channel".

[23] GSM 06.82 (ETS 300 730): "Digital cellular telecommunications system; VoiceActivity Detection (VAD)".

[24] GSM 05.09 (ETS 300 xxx): "Digital cellular telecommunications system; LinkAdaptation".

[25] GSM 06.71 (ETS 300 xxx): "Digital cellular telecommunications system; AdaptiveMulti-Rate speech processing functions, General Description."

[26] GSM 06.90 (ETS 300 xxx): "Digital cellular telecommunications system; AdaptiveMulti-Rate speech; Transcoding".

[27] GSM 06.91 (ETS 300 xxx): "Digital cellular telecommunications system; Full ratespeech; Substitution and muting of lost frames for Adaptive Multi-Rate speechchannels".

[28] GSM 06.92 (ETS 300 xxx): "Digital cellular telecommunications system; Full ratespeech; Comfort noise aspect for Adaptive Multi-Rate speech traffic channels".

[29] GSM 06.93 (ETS 300 xxx): "Digital cellular telecommunications system; Full ratespeech; Discontinuous Transmission (DTX) for Adaptive Multi-Rate speech trafficchannels".

[30] GSM 06.94 (ETS 300 xxx): "Digital cellular telecommunications system; AdaptiveMulti-Rate speech, Voice Activity Detector (VAD)".

1.2 Abbreviations

Abbreviations used in this specification are listed in GSM 01.04.

2 General Approach

When the transcoders/rate adaptors are positioned remote to the BTS, the information between the Channel CodecUnit (CCU) and the remote Transcoder/Rate Adaptor Unit (TRAU) is transferred in frames with a fixed length of320 bits (20 msS). Three different frame formats are used :- TRAU frame for full rate speech and full rate data except for 14,5 kbit/s channel coding,- B-TRAU frame for adaptive multi-rate speech,- E-TRAU frame for full rate data with 14,5 kbit/s channel coding.

In this specification, these frames are usually denoted "TRAU frames". Within these frames, both the speech/dataand the TRAU associated control signals are transferred.The Abis interface should be the same if the transcoder is positioned 1) at the MSC site of the BSS or if it ispositioned 2) at the BSC site of the BSS. In case 1), the BSC should be considered as transparent for 16 kbit/schannels.In case of 4,8 and 9,6 kbit/s channel coding when data is adapted to the 320 bit frames, a conversion function isrequired in addition to the conversion/rate adaption specified in GSM 08.20. This function constitutes the RAA. Incase of 14,5 kbit/s channel coding, no RAA rate adaption is required because V.110 framing is not used.The TRAU is considered a part of the BSC, and the signalling between the BSC and the TRAU (e.g. detection of callrelease, handover and transfer of O&M information) may be performed by using BSC internal signals. The signalling


between the CCU and the TRAU, using TRAU frames as specified in this specification, is mandatory when the Abisinterface is applied.

NOTE: If standard 64 kbit/s switching is used in the BSC, multiplexing according to CCITTRecommendation I.460 should apply at both sides of the switch.

In figure 2.1, a possible configuration of the TRAU and the CCU is shown.The functions inside the TRAU are:- "Remote Transcoder and Rate Adaptor Control Function" (RTRACF);- "Remote Speech Handler Function" (RSHF);- The RAA function in case of 4.8 and 9.6 kbit/s channel coding;- The RAA’ function in case of 14.5 kbit/s channel coding;- The RA2 function;- The transcoder function.

The functions inside the CCU are:- "Transcoder and Rate Adaptor Control Function" (TRACF);- "Speech Handler Function" (SHF);- The RAA function in case of 4.8 and 9.6 kbit/s channel coding;- The RA1/RA1' function in case of 4.8 and 9.6 kbit/s channel coding;- The RA1’/RAA’ function in case of 14.5 kbit/s channel coding;- The channel codec function.

This specification will not describe the procedures inside the TRAU and the CCU. The layout in figure 2.1 is onlyintended as a reference model.


Figure 2.1: Functional entities for handling of remote control of remote transcoders and rate adaptorsNOTE: This figure applies only for 4,8 and 9,6 kbit/s channel coding


3 Frame Structure

3.1 3.1Speech Frames

3.1.1 TRAU format (for FR and EFR)

Bit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 D1 D2 D3 D4 D5 D6 D75 D8 D9 D10 D11 D12 D13 D14 D156 1 D16 D17 D18 D19 D20 D21 D227 D23 D24 D25 D26 D27 D28 D29 D308 1 D31 D32 D33 D34 D35 D36 D379 D38 D39 D40 D41 D42 D43 D44 D4510 1 D46 D47 D48 D49 D50 D51 D5211 D53 D54 D55 D56 D57 D58 D59 D6012 1 D61 D62 D63 D64 D65 D66 D6713 D68 D69 D70 D71 D72 D73 D74 D7514 1 D76 D77 D78 D79 D80 D81 D8215 D83 D84 D85 D86 D87 D88 D89 D9016 1 D91 D92 D93 D94 D95 D96 D9717 D98 D99 D100 D101 D102 D103 D104 D10518 1 D106 D107 D108 D109 D110 D111 D11219 D113 D114 D115 D116 D117 D118 D119 D12020 1 D121 D122 D123 D124 D125 D126 D12721 D128 D129 D130 D131 D132 D133 D134 D13522 1 D136 D137 D138 D139 D140 D141 D14223 D143 D144 D145 D146 D147 D148 D149 D15024 1 D151 D152 D153 D154 D155 D156 D15725 D158 D159 D160 D161 D162 D163 D164 D16526 1 D166 D167 D168 D169 D170 D171 D17227 D173 D174 D175 D176 D177 D178 D179 D18028 1 D181 D182 D183 D184 D185 D186 D18729 D188 D189 D190 D191 D192 D193 D194 D19530 1 D196 D197 D198 D199 D200 D201 D20231 D203 D204 D205 D206 D207 D208 D209 D21032 1 D211 D212 D213 D214 D215 D216 D21733 D218 D219 D220 D221 D222 D223 D224 D22534 1 D226 D227 D228 D229 D230 D231 D23235 D233 D234 D235 D236 D237 D238 D239 D24036 1 D241 D242 D243 D244 D245 D246 D24737 D248 D249 D250 D251 D252 D253 D254 D25538 1 D256 D257 D258 D259 D260 C16 C1739 C18 C19 C20 C21 T1 T2 T3 T4

3.1.2


B-TRAU format (for AMR)

Bit number1 2 3 4 5 6 7 8

Octet no T1 T20 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 D1 D2 D3 D44 1 D5 D6 D7 D8 D9 D10 D115 D12 D13 D14 D15 D16 D17 D18 D196 D20 D21 D22 D23 D24 D25 D26 D277 D28 D29 D30 D31 D32 D33 D34 D358 C12 D36 D37 D38 D39 D40 D41 D429 D43 D44 D45 D46 D47 D48 D49 D5010 D51 D52 D53 D54 D55 D56 D57 D5811 D59 D60 D61 D62 D63 D64 D65 D6612 C13 D67 D68 D69 D70 D71 D72 D7313 D74 D75 D76 D77 D78 D79 D80 D8114 D82 D83 D84 D85 D86 D87 D88 D8915 D90 D91 D92 D93 D94 D95 D96 D9716 C14 D98 D99 D100 D101 D102 D103 D10417 D105 D106 D107 D108 D109 D110 D111 D11218 D113 D114 D115 D116 D117 D118 D119 D12019 D121 D122 D123 D124 D125 D126 D127 D12820 C15 D129 D130 D131 D132 D133 D134 D13521 D136 D137 D138 D139 D140 D141 D142 D14322 D144 D145 D146 D147 D148 D149 D150 D15123 D152 D153 D154 D155 D156 D157 D158 D15924 C16 D160 D161 D162 D163 D164 D165 D16625 D167 D168 D169 D170 D171 D172 D173 D17426 D175 D176 D177 D178 D179 D180 D181 D18227 D183 D184 D185 D186 D187 D188 D189 D19028 C17 D191 D192 D193 D194 D195 D196 D19729 D198 D199 D200 D201 D202 D203 D204 D20530 D206 D207 D208 D209 D210 D211 D212 D21331 D214 D215 D216 D217 D218 D219 D220 D22132 C18 D222 D223 D224 D225 D226 D227 D22833 D229 D230 D231 D232 D233 D234 D235 D23634 D237 D238 D239 D240 D241 D242 D243 D24435 D245 D246 D247 D248 D249 D250 D251 D25236 C19 D253 D254 D255 D256 D257 D258 D25937 D260 D261 D262 D263 D264 D265 D266 D26738 D268 D269 D270 D271 D272 D273 D274 D27539 D276 D277 D278 D279 D280 D281


3.2 O&M Frames

Bit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 D1 D2 D3 D4 D5 D6 D75 D8 D9 D10 D11 D12 D13 D14 D156 1 D16 D17 D18 D19 D20 D21 D227 D23 D24 D25 D26 D27 D28 D29 D308 1 D31 D32 D33 D34 D35 D36 D379 D38 D39 D40 D41 D42 D43 D44 D4510 1 D46 D47 D48 D49 D50 D51 D5211 D53 D54 D55 D56 D57 D58 D59 D6012 1 D61 D62 D63 D64 D65 D66 D6713 D68 D69 D70 D71 D72 D73 D74 D7514 1 D76 D77 D78 D79 D80 D81 D8215 D83 D84 D85 D86 D87 D88 D89 D9016 1 D91 D92 D93 D94 D95 D96 D9717 D98 D99 D100 D101 D102 D103 D104 D10518 1 D106 D107 D108 D109 D110 D111 D11219 D113 D114 D115 D116 D117 D118 D119 D12020 1 D121 D122 D123 D124 D125 D126 D12721 D128 D129 D130 D131 D132 D133 D134 D13522 1 D136 D137 D138 D139 D140 D141 D14223 D143 D144 D145 D146 D147 D148 D149 D15024 1 D151 D152 D153 D154 D155 D156 D15725 D158 D159 D160 D161 D162 D163 D164 D16526 1 D166 D167 D168 D169 D170 D171 D17227 D173 D174 D175 D176 D177 D178 D179 D18028 1 D181 D182 D183 D184 D185 D186 D18729 D188 D189 D190 D191 D192 D193 D194 D19530 1 D196 D197 D198 D199 D200 D201 D20231 D203 D204 D205 D206 D207 D208 D209 D21032 1 D211 D212 D213 D214 D215 D216 D21733 D218 D219 D220 D221 D222 D223 D224 D22534 1 D226 D227 D228 D229 D230 D231 D23235 D233 D234 D235 D236 D237 D238 D239 D24036 1 D241 D242 D243 D244 D245 D246 D24737 D248 D249 D250 D251 D252 D253 D254 D25538 1 D256 D257 D258 D259 D260 D261 D26239 D263 D264 S1 S2 S3 S4 S5 S6


3.3 Data Frames

3.3.1 Data Frame (for Synchronisation)

Bit number

Octet no. 1 2 3 4 5 6 7 8

0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0

2 1 C1 C2 C3 C4 C5 C6 C7

3 C8 C9 C10 C11 C12 C13 C14 C15

4 1 .

5 1 .

6 1 .


8 1 63 bits.

9 1 (72 bits including bit position 1)

10 1

11 1

12 1

13 1

14 1

15 1


17 1

18 1

19 1

20 1

21 1

22 1

23 1

24 1


26 1

27 1

28 1

29 1

30 1

31 1

32 1


34 1

35 1

36 1

37 1

38 1

39 1


3.3.2 Extended data frame (E-TRAU : data transport)

Bit number

Octet no. 1 2 3 4 5 6 7 8

0 0 0 0 0 0 0 0 0

1 0 0 0 0 0 0 0 0

2 1 C1 C2 C3 C4 C5 C6 C7

3 C8 C9 C10 C11 C12 C13 M1 M2

4 D1 D2 ...

5

6

7 Data block of 288 data bits and M1, M2.

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39 ... D287 D288


3.4 Idle Speech Frames

Bit number

Octet no. 1 2 3 4 5 6 7 80 0 0 0 0 0 0 0 01 0 0 0 0 0 0 0 02 1 C1 C2 C3 C4 C5 C6 C73 C8 C9 C10 C11 C12 C13 C14 C154 1 1 1 1 1 1 1 15 1 1 1 1 1 1 1 16 1 1 1 1 1 1 1 17 1 1 1 1 1 1 1 18 1 1 1 1 1 1 1 19 1 1 1 1 1 1 1 110 1 1 1 1 1 1 1 111 1 1 1 1 1 1 1 112 1 1 1 1 1 1 1 113 1 1 1 1 1 1 1 114 1 1 1 1 1 1 1 115 1 1 1 1 1 1 1 116 1 1 1 1 1 1 1 117 1 1 1 1 1 1 1 118 1 1 1 1 1 1 1 119 1 1 1 1 1 1 1 120 1 1 1 1 1 1 1 121 1 1 1 1 1 1 1 122 1 1 1 1 1 1 1 123 1 1 1 1 1 1 1 124 1 1 1 1 1 1 1 125 1 1 1 1 1 1 1 126 1 1 1 1 1 1 1 127 1 1 1 1 1 1 1 128 1 1 1 1 1 1 1 129 1 1 1 1 1 1 1 130 1 1 1 1 1 1 1 131 1 1 1 1 1 1 1 132 1 1 1 1 1 1 1 133 1 1 1 1 1 1 1 134 1 1 1 1 1 1 1 135 1 1 1 1 1 1 1 136 1 1 1 1 1 1 1 137 1 1 1 1 1 1 1 138 1 1 1 1 1 1 C16 C1739 C18 C19 C20 C21 T1 T2 T3 T4

3.5 Coding

In the following subclausesections, the coding of the frames is described. Any spare or not used control bits shouldbe coded binary "1".For all frame types the octet 0, 1 and the first bit of octets 2, 4, 6, 8, ... 38 are used as frame sync.


3.5.1 Coding of Speech Frames

3.5.1.1 TRAU format (for FR and EFR)

Control bits (C-bits):Description Uplink Downlink

C1C2C3C4 C5 C1C2C3C4 C5Frame type FR Speech: 0 0 0 1 0. Speech: 1 1 1 0 0(Bits C1 - C5). EFR Speech: 1 1 0 1 0 Speech: 1 1 0 1 0

Time Binary number indicating the Binary number indicatingAlignment required timing adjustment to the timing adjustment made.(Bits C6 - C11) be made in steps of 250/500 µs.

The following values apply for the codingC6C7 . . . C11 0 0 0 0 0 0 No change in frame timing 0 0 0 0 0 1 Delay frame 1 x 500 µs 0 0 0 0 1 0 Delay frame 2 x 500 µs . . . .... . . . .... 1 0 0 1 1 1 Delay frame 39 x 500 µs 1 0 1 0 0 0 Not used . . . .... 1 1 1 1 0 1 Not used 1 1 1 1 1 0 Delay frame 1 x 250 µs 1 1 1 1 1 1 Advance frame 250 µs

Frame indicators. The definition C12: BFI C12 - C15: Spareand coding of these indicators 0 : BFI = 0are given in GSM 06.31. 1 : BFI = 1 IF FR. Speech

C13 C14: SID ELSEBits C12 - C16 0 0 :SID = 0 C12: UFE

0 1 :SID = 1 0 :UFE=0 bad uplink frame 1 0 :SID = 2 1 : UFE=1 good up-link frame

Downlink Uplink Frame Error C15: TAF(UFE) C12 0 : TAF = 0(see subclause 4.8.3) 1 : TAF = 1 C13 - C15: spare

C16: Spare C16: SP 0 : SP = 0 1 : SP = 1

DTX indicator C17: DTXd C17: Spare0 : DTX not applied1 : DTX applied



Data Bits (D-bits):Bits D1 .. D260: Speech block transferred in the same order as output from the transcoder (see GSM

06.10).For Enhanced Full Rate Speech:The speech block is subdivided in five subsets. The order within a given subset is the same as output from thetranscoder (see ETS 300 726, GSM 06.60). Three parity bits are added at the end of each sub-set.These parity bits are added to the bits of the subset, according to a degenerate (shortened) cyclic code using thegenerator polynomial:

g(D) = D3 + D + 1The encoding of the cyclic code is performed in a systematic form which means that, in GF(2), the polynomial:d(m)Dn + d(m+1)Dn-1 + ......+ d(m + n-3)D3 + p(0)D2 + p(1)D + p(2)where p(0), p(1), p(2) are the parity bits, when divided by g(D), yields a remainder equal to:

1 + D + D2

For every CRC, the transmission order is p(0) first followed by p(1) and p(2) successively.Bit D1 : spare (binary "1").Bits D2...D39 : Indexes of the LSF submatrices.Bits D40...D42 : CRC over bits D1 to D22, D25 to D27 and D29.Bits D43...D95 : Indexes of the parameters of first sub-frame.Bits D96...D98 : CRC over bits D43 to D52, D91 and D92.Bits D99...D148 : Indexes of the parameters of second sub-frame.Bits D149...D151 : CRC over bits D99 to D103, D105, D144 and D145.Bits D152...D204 : Indexes of the parameters of third sub-frame.Bits D205...D207 : CRC over bits D152 to D161, D200 and D201.Bits D208...D257 : Indexes of the parameters of fourth sub-frame.Bits D258...D260 : CRC over bits D208 to D212, D214, D253 and D254.Time Alignment Bits:Bits T1 .. T4: Bits positioned at the end of the downlink frames. If the timing of the frame is to be

advanced 250 µS, these 4 bits are not transferred in order to reduce the frame lengthaccordingly. When transferred the bits are set to binary "1".


3.5.1.2 B-TRAU format (for AMR)

Control bits (C bits) :Description Uplink Downlink

Frame type C1 C2 C3 C4 C5 C1 C2 C3 C4 C5(Bits C1 - C5) AMR speech 1 0 1 0 0 AMR speech 1 0 1 0 0

Codec Mode Indication / Request C6 C7 C8 C6 C7 C8(Bits C6 - C8) 0 0 0 : 4.75 kbit/s 0 0 0 : 4.75 kbit/s

0 0 1 : 5.15 kbit/s 0 0 1 : 5.15 kbit/swhen bit RIF = 0, bits C6 to C8 0 1 0 : 5.90 kbit/s 0 1 0 : 5.90 kbit/sIndicate the Codec Mode 0 1 1 : 6.70 kbit/s 0 1 1 : 6.70 kbit/sIndication 1 0 0 : 7.40 kbit/s 1 0 0 : 7.40 kbit/s

1 0 1 : 7.95 kbit/s 1 0 1 : 7.95 kbit/swhen bit RIF = 1, bits C6 to C8 1 1 0 : 10.2 kbit/s 1 1 0 : 10.2 kbit/sIndicate the Codec Mode 1 1 1 : 12.2 kbit/s 1 1 1 : 12.2 kbit/sRequest

(Bits C9 - C11) Rx Frame Type Tx Frame TypeFrame Classification C9C10C11 C9 C10 C11(see GSM 06.93). 0 0 0 : Speech_Good 0 0 0 : Speech

0 0 1 : Speech_ Probably_Degraded

0 0 1 : Spare

0 1 0 : Speech_Bad 0 1 0 : Spare 0 1 1 : Spare 0 1 1 : Spare 1 0 0 : SID_First 1 0 0 : SID_First 1 0 1 : SID_Update 1 0 1 : SID_Update 1 1 0 : SID_Bad 1 1 0 : Spare 1 1 1 : No_Data 1 1 1 : No_Data

(Bits C12 – C19) C12 C13 = 0 0 or 0 1 or 1 0:C14..C19 carry Tandem Free Operation (TFO) information.The use of these bits is specified in ETS xxx yyy, GSM TS 08.62.

C12 C13 = 1 1:C14..C19 carry time alignment : C14 C15 C16 C17 C18 C19 1 1 1 1 1 1 No change in frame timing 1 1 1 1 1 0 Delay frame 1 x 500 µs 1 1 1 1 0 1 Delay frame 2 x 500 µs … … … … … … … … 0 1 1 0 0 0 Delay frame 39 x 500 µs 0 1 0 1 1 1 Align_CMI_CMR (see x.x.x) (*) 0 1 0 1 1 0 Not used … … … … 0 0 0 0 1 0 Not used 0 0 0 0 0 1 Delay frame 1 x 250 µs 0 0 0 0 0 0 Advance frame 250 µs(*): Command results in no change in frame timing.

Z bits (Zi, i = 1..5)Bits Zi are used for Framing Pattern Substitution. See subclause 3.7.

T1 bitThe T1 bit provides the Request or Indication Flag (RIF) information. Typically RIF toggles every frame, exceptionsee 4.6.1.3


On the uplink, it indicates if B-TRAU frame contains in the field C6-C8 the Codec Mode Indication (RIF = 0) or theCodec Mode Request (RIF = 1).On the downlink, the RIF bit is used to ensure a correct synchronization of the B-TRAU frames with the TDMAmultiframe. In downlink B-TRAU frames, RIF equals 0 on the frame that corresponds to the even radio frame whichcontains in its in-band signalling the codec mode information. When the T1 bit is skipped, assuming that it does notoccur successively more than two times, the BTS must be able to regenerate the RIF flag.

T2 bitIn uplink, the T2 bit is used to transmit the downlink DTX indicator (DTXd bit) :DTXd = 0 : DTX not appliedDTXd = 1 : DTX applied.

In downlink, the T2 bit is used to transmit the Uplink Frame Error (UFE) bit :UFE = 0 : bad uplink frameUFE = 1 : good uplink frameWhen T2 bit is skipped, the BTS considers that UFE has the same value as for the previous frame.

D bits (D1..D281)The following tables define the contents of the Data bits for all eight AMR Codec_Modes, in cases when the FrameClassification is either set to Speech_Good, or Speech_Probably_Degraded, or Speech_Bad.

The D bits are defined separately for each mode, corresponding to tables 9a to 9h in GSM TS 06.90 (ETS 300 xxx)and for the AMR SID update frame.

The CRC generator polynomial as well as its using are identical to the CRC and its corresponding using for EFRspeech frames, see subclause 3.5.1.1.

Definition of D-bits for AMR mode 12.2 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D38 : Indexes of the LSF submatrices (s1 to s38)Bits D39 .. D41 : CRC over bits D1 to D21, D24 to D26 and D28.Bit D42 : Z1 bit covering data field D5 to D41 and TF1Bits D43 .. D95 : Indexes of the parameters of the first sub-frame (s39 to s91)Bits D96 .. D98 : CRC over bits D43 to D52, D91 and D92Bit D99: Z2 bit covering data field D43 to D98, TF2 and TF3sBits D100..D149 : Indexes of the parameters of the second sub-frame (s92 to s141)Bits D150..D152 : CRC over bits D100 to D104, D106, D145 and D146.Bit D153 : Z3 bit covering data field D100 to D152 and TF4Bits D154..D206 : Indexes of the parameters of the third sub-frame (s142 to s194)Bits D207..D209 : CRC over bits D154 to D163, D202 and D203.Bit D210: Z4 bit covering data field D154 to D209, TF5 and TF6Bits D211..D260: Indexes of the parameters of the fourth sub-frame (s195 to s244)Bits D261..D263 : CRC over bits D211 to D215, D217, D256 and D257Bit D264 : Z5 bit covering data field D211 to D263, TF7 and TF8Bits D265..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D17 : Spare bits, set to “1”All the other D bits are shifted by 17 (bit D1 in uplink frame becomes D18 in downlink frame).

Definition of D-bits for AMR mode 10.2 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D26 : Indexes of the LSF subvectors (s1 to s26)Bits D27 .. D29 : CRC over bits D1 to D26Bit D30 : Z1 bit covering data field D5 to D29Bits D31 .. D76 : Indexes of the parameters of the first sub-frame (s27to s72)Bits D77 .. D79 : CRC over bits D31 to D36, D70, D71, D73and D74Bit D80 : Z2 bit covering Data bits from D31 to D79, Tf1 and Tf2Bits D81 .. D123 : Indexes of the parameters of the second sub-frame (s73 to s115)Bits D124..D126 : CRC over bits D81, D82, D117, D120 and D121Bit D127 : Z3 bit covering Data bits D81 to D126 and Tf3Bits D128..D173 : Indexes of the parameters of the third sub-frame (s116 to s161)


Bits D174..D176 : CRC over bits D128 to D135, D167, D168, D170 and D171Bit D177 : Z4 bit covering Data bits D128 to D176,Tf4 and Tf5Bits D178..D220 : Indexes of the parameters of the fourth sub-frame (s162 to s204)Bits D221..D223 : CRC over bits D178, D179, D214, D215, D217 and D218Bit D224 : Z5 bit covering Data bits D178 to D223,Tf6 and Tf7Bits D225..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D57 : Spare bits, set to “1”All the other D bits are shifted by 57 (bit D1 in uplink frame becomes D58 in downlink frame).

Definition of D-bits for AMR mode 7.95 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D27 : Indexes of the LSF subvectors (s1 to s27)Bits D28..D30 : CRC over bits D1 to D27Bit D31 : Z1 bit covering data field D5 to D29Bits D32 D65 : Indexes of the parameters of the first sub-frame (s28 to s61)Bits D66 D68 : CRC over bits D32 to D37, D57 to D59 and D61 to D64Bit D69 : Z2 bit covering Data bits from D32 to D68, Tf1 and Tf2Bits D70 D101 : Indexes of the parameters of the second sub-frame (s62 to s93)Bits D102 D104 : CRC over bits D70 to D73, D93 to D95 and D97 to D99Bit D105 : Z3 bit covering Data bits D70 to D104 and Tf3Bits D106 D139 : Indexes of the parameters of the third sub-frame (s94 to s127)Bits D140 D142 : CRC over bits D106 to D111, D131 to D133 and D135 to D138Bit D143 : Z4 bit covering Data bits D106 to D142and Tf4Bits D144 D175 : Indexes of the parameters of the fourth sub-frame (s128 to s159)Bits D176 D178 : CRC over bits D144 to D147, D167 to D169 and D171 to D174Bit D179 : Z5 bit covering Data bits D144 to D178 and Tf5Bits D180..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D102 : Spare bits, set to “1”All the other D bits are shifted by 102 (bit D1 in uplink frame becomes D103 in downlink frame).

Definition of D-bits for AMR mode 7.40 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D26 : Indexes of the LSF subvectors (s1 to s26)Bits D27..D29 : CRC over bits D1 to D26Bit D30 : Z1 bit covering data field D5 to D29Bits D31 D62 : Indexes of the parameters of the first sub-frame (s27 to s58)Bits D63 D65 : CRC over bits D31 to D36, D56, D57 and D59 to D61Bit D66 : Z2 bit covering Data bits from D31 to D65 and Tf1Bits D67 D95 : Indexes of the parameters of the second sub-frame (s59 to s87)Bits D96 D98 : CRC over bits D67 to D69, D89, D90 and D92 to D94.Bit D99 : Z3 bit covering Data bits D67 to D98, Tf2 and Tf3Bits D100 D131 : Indexes of the parameters of the third sub-frame (s88 to s119)Bits D132 D134 : CRC over bits D100 to D105, D125, D126 and D128 to D130.Bit D135 : Z4 bit covering Data bits D100 to D134and Tf4Bits D136 D164 : Indexes of the parameters of the fourth sub-frame (s120 to s148)Bits D165 D167 : CRC over bits D136 to D138, D158, D159, D161 and D162.Bit D168 : Z5 bit covering Data bits D136 to D167 and Tf5Bits D169..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D113 : Spare bits, set to “1”All the other D bits are shifted by 113 (bit D1 in uplink frame becomes D114 in downlink frame).

Definition of D-bits for AMR mode 6.70 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D26 : Indexes of the LSF subvectors (s1 to s26)Bits D27..D29 : CRC over bits D1 to D26Bit D30 : Z1 bit covering data field D5 to D29Bits D31 D59 : Indexes of the parameters of the first sub-frame (s27to s55)Bits D60 D62 : CRC over bits D31 to D38, D53, D56 and D57


Bit D63 : Z2 bit covering Data bits from D31 to D62 and Tf1Bits D64 D88 : Indexes of the parameters of the second sub-frame (s56 to s80)Bits D89 D91 : CRC over bits D64 to D67, D82, D85 and D86Bit D92 : Z3 bit covering Data bits D64 to D91 and Tf2Bits D93 D121 : Indexes of the parameters of the third sub-frame (s81 to s109)Bits D122 D124 : CRC over bits D93 to D100, D115, D118 and D119Bit D125 : Z4 bit covering Data bits D93 to D124and Tf3Bits D126 D150 : Indexes of the parameters of the fourth sub-frame (s110 to s134)Bits D151 D153 : CRC over bits D126 to D129, D144, D147 and D148.Bit D154 : Z5 bit covering Data bits D126 to D153 and Tf4Bits D155..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D127 : Spare bits, set to “1”All the other D bits are shifted by 127 (bit D1 in uplink frame becomes D128 in downlink frame).

Definition of D-bits for AMR mode 5.90 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D26 : Indexes of the LSF subvectors (s1 to s26)Bits D27..D29 : CRC over bits D1 to D26Bit D30 : Z1 bit covering data field D5 to D29Bits D31 D55 : Indexes of the parameters of the first sub-frame (s27to s51)Bits D56 D58 : CRC over bits D31 to D37 and D52 to D55.Bit D59 : Z2 bit covering Data bits from D31 to D58 and Tf1Bits D60 D80 : Indexes of the parameters of the second sub-frame (s52 to s72)Bits D81 D83 : CRC over bits D60 to D62 and D77 to D80.Bit D84 : Z3 bit covering Data bits D60 to D83 and Tf2Bits D85 D109 : Indexes of the parameters of the third sub-frame (s73 to s97)Bits D110 D111 : CRC over bits D85 to D91 and D106 to D109Bit D112 : Z4 bit covering Data bits D85 to D111and Tf3Bits D113 D133 : Indexes of the parameters of the fourth sub-frame (s98 to s118)Bits D134 D136 : CRC over bits D113 to D115 and D131 to D133Bit D137 : Z5 bit covering Data bits D113 to D136 and Tf4Bits D138..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D144 : Spare bits, set to “1”All the other D bits are shifted by 144 (bit D1 in uplink frame becomes D145 in downlink frame).

Definition of D-bits for AMR mode 5.15 kbit/s (indexing from the draft GSM 06.90)Uplink frame:Bits D1 .. D23 : Indexes of the LSF subvectors (s1 to s23)Bits D24..D26 : CRC over bits D1 to D23Bit D27 : Z1 bit covering data field D5 to D26Bits D28 D50 : Indexes of the parameters of the first sub-frame (s24 to s46)Bits D51 D53 : CRC over bits D28 to D32 and D46 to D50Bit D54 : Z2 bit covering Data bits from D28 to D53 and Tf1Bits D55 D73 : Indexes of the parameters of the second sub-frame (s47 to s65)Bits D74 D76 : CRC over bits D55, D56 and D69 to D73Bit D77 : Z3 bit covering Data bits D55 to D76 and Tf2Bits D78 D96 : Indexes of the parameters of the third sub-frame (s66 to s84)Bits D97 D99 : CRC over bits D78, D79 and D92 to D96.Bit D100 : Z4 bit covering Data bits D78 to D99 and Tf3Bits D101 D119 : Indexes of the parameters of the fourth sub-frame (s85 to s103)Bits D120 D122 : CRC over bits D101, D102 and D115 to D119.Bit D123 : Z5 bit covering Data bits D101 to D122Bits D124..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D158 : Spare bits, set to “1”All the other D bits are shifted by 158 (bit D1 in uplink frame becomes D159 in downlink frame).

Definition of D-bits for AMR mode 4.75 kbit/s (indexing from the draft GSM 06.90)Uplink frame:


Bits D1 .. D23 : Indexes of the LSF subvectors (s1 to s23)Bits D24..D26 : CRC over bits D1 to D23Bit D27 : Z1 bit covering data field D5 to D26Bits D28 D52 : Indexes of the parameters of the first sub-frame (s24 to s48)Bits D53 D55 : CRC over bits D28 to D33 and D49 to D52.Bit D56 : Z2 bit covering Data bits from D28 to D55 and Tf1Bits D57 D69 : Indexes of the parameters of the second sub-frame (s49 to s61)Bits D70 D72 : CRC over bits D57 to D69.Bit D73 : Z3 bit covering Data bits D57 to D72 and Tf2Bits D74 D94 : Indexes of the parameters of the third sub-frame (s62 to s82)Bits D95 D97 : CRC over bits D74, D75 and D91 to D94.Bit D98 : Z4 bit covering Data bits D74 to D97 and Tf3Bits D99 D111 : Indexes of the parameters of the fourth sub-frame (s83 to s95)Bits D112 D114 : CRC over bits D99 to D111.Bit D115 : Z5 bit covering Data bits D99 to D114Bits D116..D281 : Spare bits, set to “1”Downlink frame:Bits D1 .. D166 : Spare bits, set to “1”All the other D bits are shifted by 166 (bit D1 in uplink frame becomes D167 in downlink frame).

The following tables define the contents of the Data bits for all eight AMR Codec_Modes, in cases when the FrameClassification is either set to SID_First, or SID_Update, or SID_Bad, or No_Data.The three parity bits added at the end of each subset are generated using the same cyclic code as defined for theEnhanced Full Rate.

Definition of D-Bits for SID_First, uplink TRAU Frame:Bits D1 .. D35: set to "1".Bits D36 .. D38: CRC over bits D1 to D35.Bit D39 : Z1 bit covering Data bits D1 to D38 and Tf1Bits D40 .. D281: spare (242 bits); set to "1".The Downlink TRAU Frame in this SID_First has the same layout as the uplink TRAU frame.

Definition of D-Bits for SID_Update and SID_Bad, uplink TRAU Frame, see GSM 06.92, table 1:Bits D1...D3: Moving average predictor, initial values (s1..s3)Bits D4...D29: Indexes of LSF submatrices (s4..s29)Bits D30...D35: Logarithmic frame energy (s30..s35)Bits D36...D38: CRC over bits s1 to s35.Bit D39 : Z1 bit covering Data bits D1 to D38 and Tf1Bits D40...D281: spare (242 bits); set to "1"For the Downlink TRAU Frame in this SID_Update add 242 to D-bit indices (D1->D243;D39->D281). All D-bits with indices 1 to 242 are spare and set to "1".

Definition of D-Bits for No_Data, uplink TRAU Frame:Bits D1 .. D281: set to "1".The Downlink TRAU Frame in this No_Data has the same layout as the uplink TRAU frame.


3.5.2 Coding of O&M Frames

Control bits (C-bits): Description Uplink Downlink

C1C2C3C4 C5 C1C2C3C4 C5 Frame type 0 0 1 0 1 : O&M 1 1 0 1 1 : O&M Bits C1 - C5 Bits C6 - C15 Spare Spare

Data Bits (D-bits):Bits D1 .. D264: Bits used for transfer of O&M information. The coding and use of these bits are left to the

manufacturer of the BSC/TRAU.Spare Bits:Bits S1 .. S6: Spare

3.5.3 Coding of Data Frames

Control bits (C-bits):Description Uplink DownlinkFrame type. C1C2C3C4 C5 C1C2C3C4 C5Bits C1 - C5 0 1 0 0 0 : Data 1 0 1 1 0 : Data

except 14.5 except 14.5

1 0 1 0 0 : Data14.51) 1 0 1 0 0 : Data 14.51)

Intermediate RA bit 0: 8 kbit/s 0: 8 kbit/srate. 1: 16 kbit/s 1: 16 kbit/sBit C6for data servicesexcept 14.5Spare Spare Sparefor Data 14.5Bits C7 - C15 Spare Spare

NOTE 1: The Data frame is in case of data 14.5 kbit/s used only for synchronization purposes. The databits are in this case set according to subclause 4.5.1.

3.5.4 Coding of Extended Data Frames

Control bits (C-bits):Description Uplink DownlinkFrame type. C1C2C3C4 C5 C1C2C3C4 C5Bits C1 - C5 1 1 1 1 1 : 1 1 1 1 1 :

Extended Data Extended dataframe 14.5 kbit/s Frame 14.5

Bit C6Idle/Data/UFE Idle/data UFE

Frame indication


Multi Frame Structure M1, M2 M1, M2defined in GSM 04.21Bits M1, M2

3.5.5 Coding of Idle Speech Frames




Frame type. 1 0 0 0 0 : Idle Speech 0 1 1 1 0 : Idle SpeechBits C1 - C5

Bits C6 - C21 Coding as for Coding as forFR and EFR Speech speech frames. FR and EFR Speech speech frames.

Time Alignment Bits:Bits T1 .. T4: Coding as for Speech frames.

3.6. Order of Bit Transmission

The order of bit transmission is:The first octet is transferred first with the bit no. 1 first, bit no. 2 next etc.

3.7 Framing Pattern Substitution in B-TRAU frame

The Framing Pattern Substitution is used in each of five data fields of the B-TRAU frame (see subclause 3.5.1.1) toavoid transmitting a sequence of fourteen zeroes (called Z sequence in the following).The purpose of FPS is to avoid erroneous synchronisation to the B-TRAU due to fourteen zeroes occuring accidentlyin the data bits.

3.7.1 FPS encoding

A Zero Sequence Position (ZSP) field is used to account for the occurrence of fourteen zeroes in the data field.NOTE: A sequence of fourteen zeroes is considered as a block (e.g. a stream of twenty consecutive

zeroes produces only one ZSP and not two ZSPs).The ZSP field is defined as follows:

1 2 3 4 5 6 7 8 9 10 11 12 13 141 SP A0 A1 A2 A3 A4 A5 A6 A7 SP C P 1

The meaning of the different bits of the ZSP field is :C : Continuation bit. '0' means that there is another ZSP in the data field. '1' means that there is no other ZSP.

A0-A7 :address of the next Z sequence (fifteen zeroes) to be inserted. The address ‘00000001’ corresponds to the bitD1, (A0 is the msb, A7 is the lsb).

1 : locking bit prevent the false occurrence of a Z sequence.

SP : Spare bits.

The Framing Pattern Substitution is applied in each of the five data field (see subclause 3.5.1.1).Bit Zi indicates whether FPS is used in the ith data field (i=1 to 5). The coding of the Zi bit is the following:

Table 6Zi (i=1..5) meaning

1 no substitution0 at least one substitution

If Zi bit indicates no substitution, the output data bits of FPS are equal to the input data bits.


The following description indicates the general operating procedures for FPS. It is not meant to indicate arequired implementation of the encoding procedure.

1

Z S P ( a 1 )

Z S P ( a 2 )

Z S P ( a 3 )

===

C o n t i n u a t i o n B i t

n e x t Z s e qa d d r e s s

L o c k i n g b i t

Figure 3.2Step 1 :The input sub-frame is considered as a bit stream in which the bits are numbered from 1 to N.This bit stream contains 0, 1 or several Z sequences, (Zseq1 to Zseq3 on the figure)The Z sequence is a sequence of 14 consecutive zeroes : '0000 0000 0000 00'Step 2 :Starting from this bit stream, two lists are built up : 2-a : the 'a' list which contains the address of the first bit of each Z sequences.

2-d : the 'd' list which contains all the data blocks which do not have the Z sequence.

Step 3 :The 'a' list is transformed so as to build the ZSP list. Each ZSP element is used to indicate: at which address is the next Z sequence of the message

if yet another ZSP element will be found at this address (link element)

Step 4 :The output N+1 bit sub-frame is built from: the Zi field which indicates whether the original message has been transformed or not with this technique. In

the example given in Figure 3.2, Zi should be set to '0' to indicate that at least one FPS has occurred.

the ZSP and D elements interleaved.


As the ZSP elements have exactly the same length as the Z sequence, the sub frame length is onlyincreased by one (the Zi bit), whatever the number of frame pattern substitutions may be.

4 Procedures

4.1 Remote Control of Transcoders and Rate Adaptors

When the transcoder is positioned remote to the BTS, the Channel Codec Unit (CCU) in the BTS has to controlsome of the functions in the remote Transcoder/Rate Adaptor Unit (TRAU) in the BSC.This remote control is performed by inband signalling carried by the control bits (C-bits) in each TRAU frame.The following functions in the TRAU are remotely controlled by the CCU:- Shift between speech and data.- Control of the rate adaption functions for data calls.- Downlink frame timing for speech frames.- Transfer of DTX information.- Transfer of Codec Mode Request and Codec Mode Indication (AMR only).- Downlink Codec_Mode_Request / Codec_Mode_Indication Time alignment (AMR only)

In addition, the inband signalling also provides means for transfer of O&M signals between the TRAU and theBSC/BTS.

4.2 Resource Allocation

At reception of the ASSIGNMENT REQUEST message, e.g. at call setup, when a circuit switched connection isrequired, the BSC provides an appropriate TRAU to the circuit to be used between the BSC and the BTS and sendsthe CHANNEL ACTIVATION message to the BTS.When receiving the CHANnel ACTIVation message, the BTS allocates the appropriate radio resources and aChannel Codec Unit (CCU) to be used.In case of Speech or Data (except 14.5 kbit/s):

The CCU now starts sending uplink frames with the appropriate "Frame Type" and, for data calls, theintermediate rate adaption bit rate set.

When receiving the first frame, the TRAU sets the mode of operation accordingly and starts sendingdownlink frames with the "Frame Type" and, for data calls, the intermediate rate adaption bit rate set as anacknowledgement indication.

In case of Data 14.5 kbit/s:The CCU starts sending uplink Data TRAU Frames with the appropriate "Frame Type" set to establish initialsynchronization.

When receiving the first frame, the TRAU sets the mode of operation accordingly and as anacknowledgement starts sending downlink Data TRAU Frames with the same “Frame Type”.

The CCU starts sending uplink Extended Data TRAU Frames with the appropriate "Frame Type" set uponreception of that acknowledge indication.

When receiving the first frame, when the "Frame Type" is set to Extended Data TRAU frame, the TRAU setsthe mode of operation accordingly and as an acknowledgement starts sending downlink Extended Data TRAUframes with the same “Frame Type”.

4.3 Resource Release

At release of circuit switched resources, e.g. at call release, the connection between the CCU and the TRAU will bereleased by the BSC. The BSC has to indicate that the connection has been released. How this is performed is a BSCinternal matter. However, three methods have been identified.i) The BSC indicates the call release to the TRAU by inserting the PCM idle bit pattern described in GSM

08.54 on the circuits towards the TRAU. The TRAU shall be able to detect this idle bit pattern. Whenreceived at the TRAU, the TRAU will loose frame synchronization and will start timer Tsync (see section


subclause 4.8.2). If, when Tsync expires, the idle bit pattern has been detected, the TRAU shall terminate theoperation (go idle) until a valid frame is again received.

ii) This alternative does not apply to Enhanced Full Rate Speech, Data 14.5 kbit/s case.

After a call release, the TRAU downlink channel is switched to the TRAU uplink channel (16 kbit/s side).

The TRAU shall be able to detect the looped downlink frame. When it is detected, the TRAU shall terminatethe normal operation (go idle) until a valid uplink TRAU frame is again received.

iii) It is handled by BSC internal signals (e.g. if the BSC and TRAU are collocated).

4.4 In Call Modification

If the subscriber orders "In Call Modification", the CCU sets the "Frame Type" and, for data calls, the inter mediaterate adaption bit rate in the uplink frames to the new mode of operation. When receiving this information, the TRAUchanges the mode of operation accordingly and sets the new "Frame Type" and, for data calls, the intermediate rateadaption bit rate in the downlink frames. The same procedure applies for mode change between Data 14,5 kbit/s.In case of mode change to data 14,5 kbit/s from Speech or Data (other than 14.5 kbit/s) the same procedure as for“Resource Allocation” is performed.

4.5 Transfer of Idle Frames

Between the TRAU and the CCU a TRAU frame shall be transferred every 20 msS.

4.5.1 In Full rate data case:

If no data is received from the MS (uplink direction) or no data is received from the MSC side of the interface(downlink direction), idle data frames shall be transferred instead of data frames. Idle data frames are data frameswith all data bit positions set to binary "1". In addition, for 14,5 kbit/s channel coding; the C6 bit shall be set to ‘1’ inthe uplink extended data frame.

4.5.2 In Full rate speech case:

If no speech is received from the MS (uplink direction), the CCU shall send TRAU speech frames with BFI flag setto 1 (bad frame) or idle speech frames.If no speech is received from the MSC side of the interface (downlinkdirection), idle speech frames shall be transferred instead of speech frames.

4.5.3 In Enhanced Full rate speech case:

If no speech is received from the MS (uplink direction), the CCU shall send TRAU speech frames with BFI flag setto 1 (bad frame). If no speech is received from the MSC side of the interface (downlink direction), idle speechframes shall be transferred instead of speech frames.

4.5.4 In Adaptive Multi-Rate speech case:

If no speech is received from the MS (uplink direction), the CCU shall send B-TRAU speech frames with RX frametype field indicating "NO DATA", see subclause 3.5.1.2.If no speech is received from the MSC side of the interface (downlink direction), B-TRAU speech frames with TXframe type field indicating “NO DATA” shall be transferred, see subclause 3.5.1.2.

4.6 Procedures for Speech Frames

4.6.1 Time Alignment of Speech Frames

The time alignment needed for obtaining minimum buffer delay will differ from call to call. The reasons for this are:- The TRAUBSC will have no information about the radio timing at the BTS, and will start sending frames at

an arbitrary or default time. Each TRAU frame is 320 bits (20 mS) and will in the worst case be received atthe BTS 319 bits out of phase.


- The different timeslots on one carrier is sent at different times (max 4.04 mS which equals 7 timeslots in aTDMA radio frame).

- Different channels may be transferred on different transmission systems using different routes in the network.The transmission delay may therefore differ.

The required time alignment between radio frames and TRAU frames is considered to be an internal BTS matter foruplink frames. However, the buffer delay for these frames should be kept to a minimum.For downlink frames, the procedures in the following sectionsubclauses should apply. In order to describe the timealignment procedure in the TRAU, two time alignment states are described (Initial Time Alignment state and StaticTime Alignment state).In order to achieve optimum timing between the radio TDMA frames and the frames on the transmission side, thespeech coding and decoding function in the transcoder should not be synchronized.

4.6.1.1 Initial Time Alignment State

The TRAU shall enter the Initial Time Alignment state at the switching-on of the system, when it goes idle (e.g.when receiving the PCM idle pattern after a call release as described in sectionsubclause 4.3), if loss of framesynchronization is detected, in call modification from data to speech is performed or if BSS internal handover isdetected.In the initial state, the frames shall only be delayed (or no change)(see note). The transcoder is able to adjust the timefor transmitting the speech frames in steps of 125 µS (one speech sample). The CCU calculates the required timingadjustment and returns a frame including the number of 250/500 µS steps by which the frames in the downlinkdirection have to be delayed (binary number in the "Time Alignment" field).When receiving this information, the TRAU processes this data and sets the "Time Alignment" field in the nextdownlink frame as ordered and then delays the subsequent frame accordingly.

NOTE: If the TRAU, in this state, receives an order to advance the next frame 250 µS, this order shallbe interpreted as "Delay frame 39*500 µS".

When a frame is delayed due to timing adjustments, the TRAU shall fill in the gap between the frames with theappropriate number of binary "1".After having adjusted the timing, the TRAU shall receive at least three new frames before a new adjustment is made.This in order to avoid oscillation in the regulation.The TRAU shall change from the Initial Time Alignment state to the Static Time Alignment state when it hasperformed two subsequent timing adjustments which are less than 500 µS (including no change).The procedure is illustrated in figure 4.1.

4.6.1.2 The Static Time Alignment State

In the Static Time Alignment state, the TRAU performs timing adjustments in single steps of 250 µS. The timingmay either be delayed (time alignment code 111110, or 000001 for AMR), advanced (time alignment code 111111or 000000 for AMR) or not changed (time alignment code 000000 or 111111 for AMR).When receiving an order for adjusting the timing, the transcoder skips or repeats two speech samples in order toachieve the correct timing.If the timing is to be advanced 250 µS, the TRAU sets the "Time Alignment" field in the next downlink frame asordered and then the 4 last bits of the frame are not transferred (the T-bits), except for AMR for which this isachieved by skipping the T-bits of two successive B-TRAU frames.If the timing is to be delayed, the TRAU sets the "Time Alignment" field in the next downlink frame as ordered andthen delays the subsequent frame by adding four binary "1" between the frames.After having adjusted the timing, the TRAU shall receive at least three new frames before a new adjustment is made.If, in this state, the TRAU detects a change in the timing of the uplink frames bigger than n x 250 µS, where n = 4, itshall enter the Initial Time Alignment state and in that state it may perform an adjustment on the downlink equal tothe change detected on the uplink.



4.6.1.3 Time Alignment of Codec_Mode_Indication for AMR

In the Static Time Alignment state for Adaptive Multi-Rate speech it might still be necessary to align the phase of theCodec_Mode_Indication and Codec_Mode_Request as indicated in downlink TRAU frames by the RIF bit, in orderto minimise the transmission delay in downlink direction.If the phase is correct, i.e. the TRAU frames marked with RIF set to 0 are received in time for the transmission ineven speech frames on the radio interface, then no action is needed, see GSM 05.09.If the phase is not correct, then the CCU shall send one "Align_CMI_CMR" command uplink. The TRAU shall sendtwo consecutive TRAU frames with Codec_Mode_Indication (RIF set to 0 two times) and by this shall invert thephase of Codec_Mode_Indication and Codec_Mode_Request in downlink.

4.6.1.34 Initiation at Resource Allocation

When the BTS receives the CHANNEL ACTIVATION message from the BSC, it allocates the appropriate radioresources and a Channel Codec Unit (CCU). The CCU then initiates sending of speech frames (or idle speech framesif speech is not received from the MS) towards the transcoder with normal frame phase for the TDMA channel inquestion. The "Time Alignment" field in these frames is set to "no change".The TRAU will now be in the Initial Time Alignment state. When receiving the first frame it shall start sendingspeech frames (or idle speech frames) towards the BTS with arbitrary or default phase related to the uplink framephase.When receiving these frames the CCU calculates the timing adjustment required in order to achieve minimum bufferdelay and sets the "Time Alignment" field in the uplink frames accordingly.The procedures described for the Initial and for the Static Time Alignment states are then followed during the call.

4.6.1.45 Time Alignment During Handover

4.6.1.45.1 BSS External Handover

For BSS external handover, the procedure described in sectionsubclause 4.6.1.3 should be used by the newBSC/BTS at resource allocation.

4.6.1.45.2 BSS Internal Handover

If a BSS internal handover has been performed, the timing of the downlink frames may have to be adjusted severalsteps of 250/500 µS. In order to speed up the alignment of the downlink frames, this must be detected by the TRAU,e.g. by detecting the change in the uplink frame timing as described in sectionsubclause 4.6.1.2. The TRAU shouldthen enter the Initial Time Alignment state and in that state it may perform an adjustment on the downlink equal tothe change detected on the uplink.

4.6.2 Procedures for Discontinuous Transmission (DTX)

The procedures for comfort noise are described in GSM 06.12, for Full rate speech, and in GSM 06.62(ETS 300 728) for Enhanced Full rate speech and in GSM 06.92 (ETS 300 xxx) for Adaptive Multi-Rate speech.,T the overall operation of DTX is described in GSM 06.31 and, in GSM 06.81 (ETS 300 729) and in GSM 06.93(ETS 300 xxx) for respectively Full rate speech, and Enhanced Full rate speech and Adaptive Multi-Rate speech.and tThe Voice Activity Detector is described in GSM 06.32, in and GSM 06.82 (ETS 300 730) and in GSM 06.94(ETS 300 xxx) for respectively Full rate speech, and Enhanced full rate speech and Adaptive Multi-Rate speech.The DTX Handler function is considered as a part of the TRAU when remote transcoders are applied. Thespecification of the DTX Handler is given in GSM 06.31 for Full rate speech, and in GSM 06.81 (ETS 300 729) forEnhanced Full Rate speech and in GSM 06.93 (ETS 300 xxx) for Adaptive Multi-Rate speech.

4.6.2.1 DTX procedures in the uplink direction

In all frames in the uplink direction, the BFI (Bad Frame Indicator), the SID (Silence Descriptor) indicator and theTAF (Time Alignment Flag) indicator is set as output from the RSS (see GSM 06.31, and GSM 06.81(ETS 300 729) and 06.93 (ETS 300 xxx)).In the comfort noise states, the MS will transmit a new frame only every 480 msS (24 frames). These frames aretransferred in the normal way between the CCU and the TRAU. Between these frames the CCU shall transfer :- uplink idle speech frames in case of Full Rate Speech- and speech frames with BFI set to "1" in case of Enhanced Full rate Speech.


- in case of AMR, speech frames with RX frame type field indicating "NO DATA", see GSM TS 06.93 (ETS300 xxx).

4.6.2.2 DTX procedures in the downlink direction

To inform the DTX handler in the remote transcoder whether downlink DTX may be applied or not, the DTXd bit(C17) in the uplink speech frame is used. The coding is as follows:

DTXd = 0 : downlink DTX is not applied;DTXd = 1 : downlink DTX is applied.

Though this parameter is linked with the resource allocation in the BTS at call setup, its value may vary during theconnection.Full rate and Enhanced Full rate speechIn the downlink frames the SP (Speech) indicator is set as output from the TX DTX handler (see GSM 06.31 andGSM 06.81 (ETS 300 729)).If downlink DTX is not used, the SP indicator should be coded binary "1".Adaptive Multi-Rate speechIn the downlink frames the TX frame type field is set as output from the TX DTX handler, see GSM 06.93(ETS 300 xxx).

4.7 Procedures for Data Frames

4.7.1 9.6 and 4.8 kbit/s channel coding

When rate adaption to 64 Kbit/s is performed at the BTS (sub-64 kbit/s traffic channels are not used), the rateadaption between the format used on the radio interface and the 64 Kbit/s format is made by the RA1/RA1' and theRA2 function as described in GSM. 08.20. This is illustrated in figure 4.2.

•••••••• ••••••••••••••• •••• RA2 •••••••••••••• RA1 • RA1' ••••••••• • •••••••• • ••••••••••••••• • 64 Kbit/s CCITT V.110 Channel 80 bits codec frame frame

Figure GSM 08.60/4.2: Rate adaption when performed at the BTS.When sub-64 kbit/s traffic channels are used, up to four data frames are transferred in each TRAU frame. In order toconvert between the TRAU frame format and the CCITT 80 bits frame format an additional intermediate rateadaption function, RAA, is applied. This is illustrated in figure 4.3.

•••••••• ••••• Abis ••••• ••••••••••• •••• RA2 ••••••••••RAA•••••••••RAA••••• RA1•RA1'•••••• • •••••••• • ••••• • ••••• • ••••••••••• • 64 Kbit/s CCITT TRAU CCITT Channel V.110 4 X 72 + 32 V.110 codec 80 bits bits 80 bits frame frame frame frame

Figure GSM 08.60/4.3: Rate adaption when 16 kbit/s traffic channels are used

4.7.1.1 The RAA Function

The RAA function is used to convert between the CCITT V.110 80 bits frame format and the TRAU frame format.When going from the V.110 format to the TRAU frame format the first octet (all bits coded binary "0") in theCCITT V.110 80 bits frame is stripped off. Up to four such frames are then transferred in each TRAU frame asshown in sectionsubclause 3.3.When going from the TRAU frame format to the V.110 format the data frames are separated and the synchronizationoctet (all bits coded binary "0") is again included.The 80 bits V.110 frame is illustrated in figure 4.4, and the modified 72 bits frame is illustrated in figure 4.5.


Bit number Octet no. 1 2 3 4 5 6 7 8

0 0 0 0 0 0 0 0 01 1 D1 X X X X X X2 1 X X X X X X X3 1 X X X X X X X4 1 X X X X X X X5 1 X X X X X X X6 1 X X X X X X X7 1 X X X X X X X8 1 X X X X X X X9 1 X X X X X X X

Figure GSM 08.60/4.4: CCITT V.110 80 bits frame

Bit numberOctet no. 1 2 3 4 5 6 7 8

0 1 D1 X X X X X X1 1 X X X X X X X2 1 X X X X X X X3 1 X X X X X X X4 1 X X X X X X X5 1 X X X X X X X6 1 X X X X X X X7 1 X X X X X X X8 1 X X X X X X X

Figure GSM 08.60/4.5: Modified CCITT V.110 72 bits frame transferredin a TRAU data frame position

4.7.1.2 The RA1/RA1' Function

This function is described in GSM 04.21.

4.7.1.3 The RA2 Function


4.7.1.4 Procedures for 8 kbit/s intermediate rate adaption rate

For 8 kbit/s intermediate rate adaption rate up to two data frames are transferred in each TRAU frame. The first dataframe is transferred in TRAU data frame position 1 and the subsequent data frame is transferred in TRAU data frameposition 3 (see sectionsubclause 3.3).In TRAU data frame position 2 and 4, all bits are coded binary "1".If the data transfer terminates before the TRAU frame has been completed, the remaining data bit positions in theTRAU frame should be coded binary "1".

4.7.1.5 Procedures for 16 kbit/s intermediate rate adaption rate

For 16 kbit/s intermediate rate adaption rate, up to four data frames are transferred in each TRAU frame. The firstdata frame is transferred in TRAU data frame position 1, the next in data frame position 2 etc.If the data transfer terminates before the TRAU frame has been completed, the remaining data bit positions in theTRAU frame should be coded binary "1".

4.7.1.6 Support of Non-Transparent Bearer Applications

In GSM 08.20, the procedures for transfer of non-transparent bearer applications are specified. The 240 bit RLPframe is converted to four modified V.110 80 bit frames.The same conversion is applied when transferred in a TRAU frame. The frames are coded as specified insectionsubclauses 4.7.4 and 4.7.5.


4.7.2 14.5 kbit/s channel coding

When rate adaption to 64 Kbit/s is performed at the BTS (sub-64 kbit/s traffic channels are not used), the rateadaption between the format used on the radio interface and the 64 Kbit/s format is as described in GSM 08.20.When sub-64 kbit/s traffic channels are used, up to eight 36 bits frames are transferred in each E-TRAU frame. Inorder to convert between the E-TRAU frame format and the 36 bits frame format used for the radio interface anadditional intermediate rate adaption function, RA1’/RAA’, is applied. This is illustrated in figure 4.3.1 (see alsoGSM 08.20).

•••••••• •••••• Abis •••••••••••• •••• RA2 ••••••••••RAA'•••••••••••••••• RAA'•RA1'•••••• • •••••••• • •••••• • •••••••••••• • 64 Kbit/s A-TRAU E-TRAU Radio 8 X 36 + 32 320 Interface bits bits frame frame frame

Figure GSM 08.60/4.3.1: Rate adaption when 16 kbit/s traffic channels are used

4.7.2.1 The RAA’ Function

See GSM 08.20

4.7.2.2 The RA1’/RAA' Function


4.7.2.3 The RA2 Function


4.8 Frame Synchronization

4.8.1 Search for Frame Synchronization

TRAU formatThe frame synchronization is obtained by means of the first two octets in each frame, with all bits coded binary "0",and the first bit in octet no. 2, 4, 6, 8, ... 38 coded binary "1". The following 35 bit alignment pattern is used toachieve frame synchronization:

00000000 00000000 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX

B-TRAU formatThe frame synchronization is obtained by means of the first two octets in each frame, with all bits coded binary "0",and the first bit in octets no. 2 and 4 coded binary "1". The following 18 bit alignment pattern is used to achieveframe synchronization:

00000000 00000000 1XXXXXXX XXXXXXXX 1XXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX

4.8.2 Frame Synchronization After Performing Downlink Timing Adjustments

If the timing of the downlink speech frames is adjusted, the adjustment is indicated in bits C6 - C11 for Full rate andEnhanced Full rate and in bits C12 – C19 for Adaptive Multi-Rate as described in sectionsubclauses 4.6.1.1 and4.6.1.2. The frame synchronization unit shall change its frame synchronization window accordingly.


4.8.3 Frame Synchronization Monitoring and Recovery

The monitoring of the frame synchronization shall be a continuous process.Loss of frame synchronization shall not be assumed unless at least three consecutive frames, each with at least oneframing bit error, are detected.In case of Full Rate speech:

If the TRAU looses its frame synchronization it starts a timer Tsync = 1 second. If Tsync expires beforeframe synchronization is again obtained the TRAU initiates sending of the urgent alarm pattern described insectionsubclause 4.10.2.

The exception from this procedure is when "Resource Release" is detected while Tsync is running (seesectionsubclause 4.3). In this case, the procedure in sectionsubclause 4.3 shall be followed.

If loss of frame synchronization is detected by the CCU it starts a timer Tsync. If Tsync expires before framesynchronization is again obtained the call shall be released and an indication given to O&M.

Tsync is reset every time frame synchronization is again obtained.

In case of Enhanced full rate speech and Adaptive Multi-Rate speech:When it detects a framing bit error, the TRAU uses the control bit UFE (uplink Frame Error) in the nextdownlink TRAU frame to indicate it to the CCU. When the CCU receives a TRAU frame indicating anUplink Frame Error and which has no errors on the sychronization pattern and the control bits, it starts a timerTsyncU.

If loss of frame sychronization is detected by the CCU it starts a timer TsyncD. If TsyncD or TsyncU expiresbefore frame sychronization is again obtained, the call shall be released as specified in GSM 08.58 with thecase field set to " Remote Transcoder Failure".

TsyncD is reset every time frame synchronisation is again obtained.

TsychU is reset every time three consecutive TRAU frames are received without Uplink Frame Errorindication, without errors on the frame synchronisation pattern and on the control bits.

TsyncD and TsyncU are parameters set by O&M (default value = 1 second).

In case of Data 14.5 kbit/s:The following 17 bit alignment pattern of the Extended Data TRAU Frame is used for Frame SynchronizationMonitoring:

00000000 00000000 1XXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXXXXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX

When it detects a framing bit error, the TRAU uses the control bit UFE (uplink Frame Error) in the nextdownlink Extended Data TRAU Frame to indicate it to the CCU. When the CCU receives an Extended DataTRAU Frame indicating an Uplink Frame Error and which has no errors on the synchronization pattern andthe control bits, it starts a timer TsyncU and TsyncR.

If loss of frame synchronization is detected by the CCU it starts a timer TsyncD and starts sending DataTRAU Frames in the uplink direction to trigger the TRAU to start sending Data TRAU Frames in thedownlink direction to be used for downlink Synchronization Recovery.

If TsyncR expires before frame synchronization is again obtained, the CCU starts sending Data TRAUFrames in the uplink direction to be used for uplink Synchronization Recovery.

If TsyncD or TsyncU expires before frame synchronization is again obtained, the call shall be released asspecified in GSM 08.58 with the case field set to " Remote Transcoder Failure".

TsyncD is reset every time frame synchronization is again obtained.


TsychU and TsyncR is reset every time three consecutive TRAU frames are received without Uplink FrameError indication, without errors on the frame synchronization pattern and on the control bits.

TsyncD and TsyncU are parameters set by O&M (default value = 1 second)

TsyncR are a parameter set by O&M (default value = 60 milliseconds).

4.9 Correction/detection of bit errors on the terrestrial circuits

4.9.1 Error Detection on the Control Bits

For the control bits, (C-bits), no error coding is made. However, in order to reduce the possibility ofmisinterpretation of control information due to bit errors, the following procedure should be followed.

4.9.1.1 General Procedure

If any undefined combination of the C-bits is received (see sectionsubclause 3.5), the frame should be reacted uponas received with errors.

4.9.1.2 Speech Frames

In addition to the general procedure described in the previous sectionsubclause, the following procedure should befollowed for the speech frames:Bits C6 - C11 or Bits C12 – C19 for AMR: Time Alignment.The full range of the time alignment adjustment should only be applied when the TRAU is in the Initial TimeAlignment state (see sectionsubclauses 4.6.1.1 and 4.6.1.2).If, in the Static Time Alignment state, a time alignment order is received indicating an adjustment of more than 250µS, the next downlink frame should be delayed only one 250 µS step.If an uplink frame is received with the "Time Alignment" field set to an unused value (101000 ... 111101 or 010110… 000010 for AMR), this value should be interpreted as "no change".

4.9.2 Handling of frames received with errors

If TRAU frame is received in the uplink or downlink with detectable errors in the control bits, then the controlinformation shall be ignored. The speech or data bits shall be handled as if no error had been detected.If frame synchronisation has been lost (see sectionsubclause 4.8.3) in the uplink direction the TRAU shall:- for speech, mute the decoded speech as if it has received frames with errors (cf. GSM 06.11, and GSM 06.61

(ETS 300 727) and GSM 06.91 (ETS 300 xxx));

- for data, send idle frames as defined in GSM 08.20 to the MSC/interworking.

4.9.2.1 In case of Full Rate:

If frame synchronisation has been lost in the downlink direction then the same procedure shall be followed as whenframe synchronisation is lost on the PCM link.

4.9.2.2 In case of Enhanced Full rate and Adaptive Multi-Rate :

For speech calls, the CCU shall transmit a layer two fill frame on the air interface if frame synchronization has beenlost in the downlink direction.If a CRC error is detected in a downlink TRAU speech frame a solution can be to transmit a layer two fill frame onthe air interface, another solution can be to replace the bad part of the TRAU speech frame only. The choice of thesolution is left open.If a CRC error is detected in a uplink TRAU speech frame, the TRAU speech frame shall be regarded as bad orpartly bad and the TRAU shall apply the procedure defined in GSM 06.61 (ETS 300 727) for Enhanced Full rate andin GSM 06.yy (ETS 300 xxx) for Adaptive Multi-Rate.


4.10 Procedures for Operation & Maintenance

The general procedures for Operation and Maintenance are described in GSM 12.21.If the transcoders are positioned outside the BTS, some O&M functions will be required for the TRAU and the CCU.In particular this applies for transcoders positioned at the MSC site.The transcoders outside the BTS are considered a part of the BSC, and the O&M functions for the TRAU shouldtherefore be implemented in the BSC.The CCU is a part of the BTS and the O&M functions for this unit should therefore be implemented in the BTS.

4.10.1 Transfer of O&M Information Between the TRAU and the BSC

The transfer of O&M information between the BSC and the TRAU is possible to do in two ways. Either it is handleddirectly between the BSC and the TRAU or a BTS is used as a message transfer point. The choice between the twomethods is up to the manufacturer of the BSC:i) The transfer of O&M information between the BSC and the TRAU is handled internally by the BSC. The

O&M signalling between the TRAU and the BSC may either be handled by proprietary BSC solutions or theO&M TRAU frames defined in sectionsubclauses 3.2 and 3.5.2 could be used. In the latter case, the BSC hasto act as a terminal for the O&M TRAU frames sent between the TRAU and the BSC.

ii) The O&M information between the TRAU and the BSC is transferred using O&M TRAU frames between theTRAU and the CCU in a BTS. The BTS then acts as a relay function between the O&M TRAU frames andthe associated O&M messages sent between the BTS and the BSC.

4.10.2 Procedures in the TRAU

In case of urgent fault conditions in the TRAU, e.g. loss of frame synchronization, non-ability of the transcoder toprocess data etc., this should if possible, be signalled to the BTS/BSC as an urgent alarm pattern. The urgent alarmpattern is a continuous stream of binary "0".If O&M TRAU frames information between the TRAU and the BSC is transferred using O&M frames between theCCU in a BTS and the TRAU, the TRAU sends O&M frames periodically until the identical O&M TRAU frame isreceived for acknowledgement. The period is at least 64*20ms (1,28 sec).In case of minor fault conditions, when no immediate action is required, the TRAU may send O&M framesindicating the fault instead of the urgent alarm pattern.

4.10.3 Procedures in the BSC

The BSC should be able to detect a faulty TRAU, take it out of service and give an indication to O&M. A faultyTRAU could be detected e.g. by routine tests, alarms from the TRAU, release of call initiated by the BTS due toremote transcoder failure etc. How this is handled by the BSC is regarded as a BSC internal matter.

4.10.3.1 Use of O&M Frames

The use and coding of O&M TRAU frames is left to the implementor of the BSC/TRAU.If O&M TRAU frames are used, they are always carrying 264 data bits.Any corresponding O&M message between the BSC and the BTS shall always carry all 264 O&M data bits.

4.10.4 Procedures in the BTS

If a CCU in a BTS receives O&M TRAU frames from the TRAU, the BTS shall:- send the identical frame to the TRAU for acknowledgement; and

- put the 264 data bits from the received frames into an appropriate O&M message and send it to the BSC.

If the CCU receives O&M frames during a call then "stolen frames" shall be indicated to the MS and layer 2 framesof format A (see GSM 04.06) shall be transmitted.If the CCU receives O&M frames during a data call, then the same procedure shall be used as when V.110 frame islost.If receiving an O&M message from the BSC, carrying TRAU O&M information, the BTS puts the 264 data bitsfrom the received message into an O&M TRAU frame and then the CCU allocated to the addressed connectionsends the frame to the TRAU in one single O&M TRAU frame. Repetition is done according to GSM 12.21.


In case of a faulty CCU, the O&M procedures are BTS internal.If the CCU receives the urgent alarm pattern, the BTS shall initiate release of the call as specified in GSM 08.58with the cause field set to "Remote Transcoder Failure".

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16 kbit/s TRAU frame format for the AMR speech · PDF file16 kbit/s TRAU frame format for the AMR speech service ... 4.7.1.5 Procedures for 16 kbit/s intermediate rate adaption rate